diff --git a/api/boinc_api.cpp b/api/boinc_api.cpp
index c7bcacd844..26e451e7da 100644
--- a/api/boinc_api.cpp
+++ b/api/boinc_api.cpp
@@ -193,17 +193,18 @@ static void boinc_exit(int);
 static void block_sigalrm();
 static int start_worker_signals();
 
-char* boinc_msg_prefix(char* sbuf) {
+char* boinc_msg_prefix(char* sbuf, int len) {
     char buf[256];
 
     time_t x = time(0);
     struct tm* tm = localtime(&x);
     strftime(buf, sizeof(buf)-1, "%H:%M:%S", tm);
 #ifdef _WIN32
-    sprintf(sbuf, "%s (%d):", buf, GetCurrentProcessId());
+    snprintf(sbuf, len, "%s (%d):", buf, GetCurrentProcessId());
 #else
-    sprintf(sbuf, "%s (%d):", buf, getpid());
+    snprintf(sbuf, len, "%s (%d):", buf, getpid());
 #endif
+    sbuf[len-1] = 0;    // just in case
     return sbuf;
 }
 
@@ -212,7 +213,7 @@ static int setup_shared_mem() {
     if (standalone) {
         fprintf(stderr,
             "%s Standalone mode, so not using shared memory.\n",
-            boinc_msg_prefix(buf)
+            boinc_msg_prefix(buf, sizeof(buf))
         );
         return 0;
     }
@@ -367,7 +368,7 @@ int boinc_init_options_general(BOINC_OPTIONS& opt) {
             // give any previous occupant a chance to timeout and exit
             //
             fprintf(stderr, "%s Can't acquire lockfile (%d) - waiting %ds\n",
-                boinc_msg_prefix(buf),
+                boinc_msg_prefix(buf, sizeof(buf)),
                 retval, LOCKFILE_TIMEOUT_PERIOD
             );
             boinc_sleep(LOCKFILE_TIMEOUT_PERIOD);
@@ -375,13 +376,13 @@ int boinc_init_options_general(BOINC_OPTIONS& opt) {
         }
         if (retval) {
             fprintf(stderr, "%s Can't acquire lockfile (%d) - exiting\n",
-                boinc_msg_prefix(buf),
+                boinc_msg_prefix(buf, sizeof(buf)),
                 retval
             );
 #ifdef _WIN32
-            char buf[256];
-            windows_error_string(buf, 256);
-            fprintf(stderr, "%s Error: %s\n", boinc_msg_prefix(buf), buf);
+            char buf2[256];
+            windows_error_string(buf2, 256);
+            fprintf(stderr, "%s Error: %s\n", boinc_msg_prefix(buf, sizeof(buf)), buf2);
 #endif
             // if we can't acquire the lock file there must be
             // another app instance running in this slot.
@@ -400,7 +401,7 @@ int boinc_init_options_general(BOINC_OPTIONS& opt) {
         if (retval) {
             fprintf(stderr,
                 "%s Can't set up shared mem: %d. Will run in standalone mode.\n",
-                boinc_msg_prefix(buf), retval
+                boinc_msg_prefix(buf, sizeof(buf)), retval
             );
             standalone = true;
         }
@@ -463,7 +464,10 @@ static void send_trickle_up_msg() {
 int boinc_finish(int status) {
     char buf[256];
     fraction_done = 1;
-    fprintf(stderr, "%s called boinc_finish\n", boinc_msg_prefix(buf));
+    fprintf(stderr,
+        "%s called boinc_finish\n",
+        boinc_msg_prefix(buf, sizeof(buf))
+    );
     boinc_sleep(2.0);   // let the timer thread send final messages
     g_sleep = true;     // then disable it
 
@@ -509,11 +513,12 @@ void boinc_exit(int status) {
             windows_error_string(buf, 256);
             fprintf(stderr,
                 "%s Can't unlock lockfile (%d): %s\n",
-                boinc_msg_prefix(buf), retval, buf
+                boinc_msg_prefix(buf, sizeof(buf)), retval, buf
             );
 #else
             fprintf(stderr,
-                "%s Can't unlock lockfile (%d)\n", boinc_msg_prefix(buf), retval
+                "%s Can't unlock lockfile (%d)\n",
+                boinc_msg_prefix(buf, sizeof(buf)), retval
             );
             perror("file unlock failed");
 #endif
@@ -556,7 +561,7 @@ static void exit_from_timer_thread(int status) {
 #ifdef DEBUG_BOINC_API
     char buf[256];
     fprintf(stderr, "%s exit_from_timer_thread(%d) called\n",
-        boinc_msg_prefix(buf), status
+        boinc_msg_prefix(buf, sizeof(buf)), status
     );
 #endif
 #ifdef _WIN32
@@ -595,7 +600,7 @@ int boinc_parse_init_data_file() {
     if (!boinc_file_exists(INIT_DATA_FILE)) {
         fprintf(stderr,
             "%s Can't open init data file - running in standalone mode\n",
-            boinc_msg_prefix(buf)
+            boinc_msg_prefix(buf, sizeof(buf))
         );
         return ERR_FOPEN;
     }
@@ -605,7 +610,7 @@ int boinc_parse_init_data_file() {
     if (retval) {
         fprintf(stderr,
             "%s Can't parse init data file - running in standalone mode\n",
-            boinc_msg_prefix(buf)
+            boinc_msg_prefix(buf, sizeof(buf))
         );
         return retval;
     }
@@ -723,7 +728,7 @@ static void handle_upload_file_status() {
         if (!f) {
             fprintf(stderr,
                 "%s handle_file_upload_status: can't open %s\n",
-                boinc_msg_prefix(buf), filename.c_str()
+                boinc_msg_prefix(buf, sizeof(buf)), filename.c_str()
             );
             continue;
         }
@@ -736,7 +741,7 @@ static void handle_upload_file_status() {
             upload_file_status.push_back(uf);
         } else {
             fprintf(stderr, "%s handle_upload_file_status: can't parse %s\n",
-                boinc_msg_prefix(log_buf), buf
+                boinc_msg_prefix(log_buf, sizeof(log_buf)), buf
             );
         }
     }
@@ -765,7 +770,7 @@ static void handle_process_control_msg() {
 #ifdef DEBUG_BOINC_API
         char log_buf[256]
         fprintf(stderr, "%s got process control msg %s\n",
-            boinc_msg_prefix(log_buf), buf
+            boinc_msg_prefix(log_buf, sizeof(log_buf)), buf
         );
 #endif
         if (match_tag(buf, "<suspend/>")) {
@@ -937,7 +942,8 @@ static void timer_handler() {
 #ifdef DEBUG_BOINC_API
     if (in_critical_section) {
         fprintf(stderr,
-            "%s: timer_handler(): in critical section\n", boinc_msg_prefix(buf)
+            "%s: timer_handler(): in critical section\n",
+            boinc_msg_prefix(buf, sizeof(buf))
         );
     }
 #endif
@@ -962,7 +968,7 @@ static void timer_handler() {
     if (interrupt_count % TIMERS_PER_SEC) return;
 
 #ifdef DEBUG_BOINC_API
-    fprintf(stderr, "%s 1 sec elapsed\n", boinc_msg_prefix(buf));
+    fprintf(stderr, "%s 1 sec elapsed\n", boinc_msg_prefix(buf, sizeof(buf)));
 #endif
 
     // here it we're at a one-second boundary; do slow stuff
@@ -982,7 +988,7 @@ static void timer_handler() {
         if (heartbeat_giveup_time < interrupt_count) {
             fprintf(stderr,
                 "%s No heartbeat from core client for 30 sec - exiting\n",
-                boinc_msg_prefix(buf)
+                boinc_msg_prefix(buf, sizeof(buf))
             );
             if (options.direct_process_action) {
                 exit_from_timer_thread(0);
@@ -1092,7 +1098,7 @@ int start_timer_thread() {
     if (!CreateThread(NULL, 0, timer_thread, 0, 0, &timer_thread_id)) {
         fprintf(stderr,
             "%s start_timer_thread(): CreateThread() failed, errno %d\n",
-            boinc_msg_prefix(buf), errno
+            boinc_msg_prefix(buf, sizeof(buf)), errno
         );
         return errno;
     }
@@ -1110,7 +1116,7 @@ int start_timer_thread() {
     if (retval) {
         fprintf(stderr,
             "%s start_timer_thread(): pthread_create(): %d",
-            boinc_msg_prefix(buf), retval
+            boinc_msg_prefix(buf, sizeof(buf)), retval
         );
         return retval;
     }
diff --git a/api/boinc_api.h b/api/boinc_api.h
index 3fda1830b3..c677fa3a0c 100644
--- a/api/boinc_api.h
+++ b/api/boinc_api.h
@@ -125,7 +125,7 @@ extern int boinc_wu_cpu_time(double&);
 extern double boinc_elapsed_time();
 extern int boinc_upload_file(std::string& name);
 extern int boinc_upload_status(std::string& name);
-extern char* boinc_msg_prefix(char*);
+extern char* boinc_msg_prefix(char*, int);
 
 /////////// API ENDS HERE
 
diff --git a/api/graphics2_unix.cpp b/api/graphics2_unix.cpp
index 1492f1a3bd..54ef2556dc 100644
--- a/api/graphics2_unix.cpp
+++ b/api/graphics2_unix.cpp
@@ -54,7 +54,7 @@ bool fullscreen;
 
 void boinc_close_window_and_quit(const char* p) {
     char buf[256];
-    fprintf(stderr, "%s Quitting: %s\n", boinc_msg_prefix(buf), p);
+    fprintf(stderr, "%s Quitting: %s\n", boinc_msg_prefix(buf, sizeof(buf)), p);
     exit(0);
 }
 
diff --git a/api/graphics2_win.cpp b/api/graphics2_win.cpp
index c0d01d5c99..fa082310c2 100644
--- a/api/graphics2_win.cpp
+++ b/api/graphics2_win.cpp
@@ -52,7 +52,7 @@ static bool fullscreen;
 void boinc_close_window_and_quit(const char* p) {
     char buf[256];
     fprintf(stderr, "%s Close event (%s) detected, shutting down.\n",
-        boinc_msg_prefix(buf), p
+        boinc_msg_prefix(buf, sizeof(buf)), p
     );
 
     window_ready = false;
@@ -105,7 +105,7 @@ void SetupPixelFormat(HDC win_dc) {
     if (!SetPixelFormat(win_dc, nPixelFormat, &pfd)) {
         fprintf(stderr,
             "%s ERROR: Couldn't set pixel format for device context (0x%x).\n",
-            boinc_msg_prefix(buf), GetLastError()
+            boinc_msg_prefix(buf, sizeof(buf)), GetLastError()
         );
     }
 }
@@ -168,14 +168,14 @@ static void make_window(const char* title) {
     if (!SetForegroundWindow(window)) {
         fprintf(stderr,
             "%s ERROR: SetForegroundWindow() failed (0x%x).\n",
-            boinc_msg_prefix(buf), GetLastError()
+            boinc_msg_prefix(buf, sizeof(buf)), GetLastError()
         );
     }
 
     if (!GetCursorPos(&mousePos)) {
         fprintf(stderr,
             "%s ERROR: GetCursorPos() failed (0x%x).\n",
-            boinc_msg_prefix(buf), GetLastError()
+            boinc_msg_prefix(buf, sizeof(buf)), GetLastError()
         );
     }
 
@@ -183,7 +183,7 @@ static void make_window(const char* title) {
     if (!win_dc) {
         fprintf(stderr,
             "%s ERROR: GetDC() failed (0x%x).\n",
-            boinc_msg_prefix(buf), GetLastError()
+            boinc_msg_prefix(buf, sizeof(buf)), GetLastError()
         );
     }
     SetupPixelFormat(win_dc);
@@ -192,7 +192,7 @@ static void make_window(const char* title) {
     if (!gl_dc) {
         fprintf(stderr,
             "%s ERROR: wglCreateContext() failed (0x%x).\n",
-            boinc_msg_prefix(buf), GetLastError()
+            boinc_msg_prefix(buf, sizeof(buf)), GetLastError()
         );
         ReleaseDC(window, win_dc);
         return;
@@ -201,7 +201,7 @@ static void make_window(const char* title) {
     if(!wglMakeCurrent(win_dc, gl_dc)) {
         fprintf(stderr,
             "%s ERROR: wglMakeCurrent() failed (0x%x).\n",
-            boinc_msg_prefix(buf), GetLastError()
+            boinc_msg_prefix(buf, sizeof(buf)), GetLastError()
         );
         ReleaseDC(window, win_dc);
         wglDeleteContext(gl_dc);
@@ -416,13 +416,16 @@ void boinc_graphics_loop(int argc, char** argv, const char* title) {
         boinc_init_graphics_diagnostics(BOINC_DIAG_DEFAULTS);
     }
 
-    fprintf(stderr, "%s Starting graphics application.\n", boinc_msg_prefix(buf));
+    fprintf(stderr,
+        "%s Starting graphics application.\n",
+        boinc_msg_prefix(buf, sizeof(buf))
+    );
 
     for (int i=1; i<argc; i++) {
         if (!strcmp(argv[i], "--fullscreen")) {
             fullscreen = true;
             fprintf(stderr, "%s fullscreen mode requested.\n",
-                boinc_msg_prefix(buf)
+                boinc_msg_prefix(buf, sizeof(buf))
             );
         }
     }
@@ -450,7 +453,7 @@ void boinc_graphics_loop(int argc, char** argv, const char* title) {
     unreg_win_class();
 
     fprintf(stderr, "%s Shutting down graphics application.\n",
-        boinc_msg_prefix(buf)
+        boinc_msg_prefix(buf, sizeof(buf))
     );
 }
 
diff --git a/apps/upper_case.cpp b/apps/upper_case.cpp
index e2753bf350..fdcbd06d18 100644
--- a/apps/upper_case.cpp
+++ b/apps/upper_case.cpp
@@ -151,7 +151,7 @@ int main(int argc, char **argv) {
     retval = boinc_init();
     if (retval) {
         fprintf(stderr, "%s boinc_init returned %d\n",
-            boinc_msg_prefix(buf), retval
+            boinc_msg_prefix(buf, sizeof(buf)), retval
         );
         exit(retval);
     }
@@ -163,7 +163,7 @@ int main(int argc, char **argv) {
     if (!infile) {
         fprintf(stderr,
             "%s Couldn't find input file, resolved name %s.\n",
-            boinc_msg_prefix(buf), input_path
+            boinc_msg_prefix(buf, sizeof(buf)), input_path
         );
         exit(-1);
     }
@@ -192,10 +192,10 @@ int main(int argc, char **argv) {
     }
     if (retval) {
         fprintf(stderr, "%s APP: upper_case output open failed:\n",
-            boinc_msg_prefix(buf)
+            boinc_msg_prefix(buf, sizeof(buf))
         );
         fprintf(stderr, "%s resolved name %s, retval %d\n",
-            boinc_msg_prefix(buf), output_path, retval
+            boinc_msg_prefix(buf, sizeof(buf)), output_path, retval
         );
         perror("open");
         exit(1);
@@ -207,7 +207,7 @@ int main(int argc, char **argv) {
     shmem = (UC_SHMEM*)boinc_graphics_make_shmem("uppercase", sizeof(UC_SHMEM));
     if (!shmem) {
         fprintf(stderr, "%s failed to create shared mem segment\n",
-            boinc_msg_prefix(buf)
+            boinc_msg_prefix(buf, sizeof(buf))
         );
     }
     update_shmem();
@@ -243,7 +243,7 @@ int main(int argc, char **argv) {
             retval = do_checkpoint(out, nchars);
             if (retval) {
                 fprintf(stderr, "%s APP: upper_case checkpoint failed %d\n",
-                    boinc_msg_prefix(buf), retval
+                    boinc_msg_prefix(buf, sizeof(buf)), retval
                 );
                 exit(retval);
             }
@@ -258,7 +258,7 @@ int main(int argc, char **argv) {
     retval = out.flush();
     if (retval) {
         fprintf(stderr, "%s APP: upper_case flush failed %d\n",
-            boinc_msg_prefix(buf), retval
+            boinc_msg_prefix(buf, sizeof(buf)), retval
         );
         exit(1);
     }
@@ -277,7 +277,7 @@ int main(int argc, char **argv) {
                 retval = do_checkpoint(out, nchars);
                 if (retval) {
                     fprintf(stderr, "%s APP: upper_case checkpoint failed %d\n",
-                        boinc_msg_prefix(buf), retval
+                        boinc_msg_prefix(buf, sizeof(buf)), retval
                     );
                     exit(1);
                 }
diff --git a/checkin_notes b/checkin_notes
index a75cbc5895..341fdbf29c 100644
--- a/checkin_notes
+++ b/checkin_notes
@@ -6596,3 +6596,17 @@ David  15 Sept 2010
 
     lib/
         gui_rpc_client.cpp
+
+David  15 Sept 2010
+    - API and sample apps: pass buf length arg to boinc_msg_prefix()
+        and use snprintf() to avoid overrun.
+        Can't see why this could ever happen.
+        Attempt to fix crash in E@h apps.
+
+    apps/
+        upper_case.cpp
+    samples/*/*.cpp
+    api/
+        boinc_api.cpp,h
+        graphics2_unix.cpp
+        graphics2_win.cpp
diff --git a/samples/atiopencl/atiopencl.cpp b/samples/atiopencl/atiopencl.cpp
index acdf80e043..85eaa4626c 100644
--- a/samples/atiopencl/atiopencl.cpp
+++ b/samples/atiopencl/atiopencl.cpp
@@ -58,7 +58,7 @@ int main(int argc, char * argv[]) {
     retval = boinc_init();
     if (retval) {
         fprintf(stderr, "%s boinc_init returned %d\n",
-                boinc_msg_prefix(buf), retval );
+                boinc_msg_prefix(buf, sizeof(buf)), retval );
         exit(retval);
     }
     
@@ -69,7 +69,7 @@ int main(int argc, char * argv[]) {
     if (!infile) {
         fprintf(stderr,
             "%s Couldn't find input file in boinc\\win_build, resolved name %s.\n",
-            boinc_msg_prefix(buf), input_path
+            boinc_msg_prefix(buf, sizeof(buf)), input_path
         );
         getchar();
         exit(-1);
@@ -102,10 +102,10 @@ int main(int argc, char * argv[]) {
 
     if (retval) {
         fprintf(stderr, "%s APP: matrix_inversion output open failed:\n",
-            boinc_msg_prefix(buf)
+            boinc_msg_prefix(buf, sizeof(buf))
         );
         fprintf(stderr, "%s resolved name %s, retval %d\n",
-            boinc_msg_prefix(buf), output_path, retval
+            boinc_msg_prefix(buf, sizeof(buf)), output_path, retval
         );
         perror("open");
         exit(1);
@@ -117,7 +117,7 @@ int main(int argc, char * argv[]) {
     shmem = (UC_SHMEM*)boinc_graphics_make_shmem("matrix_inversion", sizeof(UC_SHMEM));
     if (!shmem) {
         fprintf(stderr, "%s failed to create shared mem segment\n",
-            boinc_msg_prefix(buf)
+            boinc_msg_prefix(buf, sizeof(buf))
         );
     }
     update_shmem();
@@ -180,7 +180,7 @@ int main(int argc, char * argv[]) {
             retval = do_checkpoint(out, i, input, matrixSize); 
             if (retval) {
                 fprintf(stderr, "%s APP: matrix_inversion checkpoint failed %d\n",
-                    boinc_msg_prefix(buf), retval
+                    boinc_msg_prefix(buf, sizeof(buf)), retval
                 );
                 exit(retval);
             }
@@ -198,7 +198,7 @@ int main(int argc, char * argv[]) {
     retval = out.flush(); //force the output file to be closed.
     if (retval) {
         fprintf(stderr, "%s APP: matrix_inversion flush failed %d\n",
-            boinc_msg_prefix(buf), retval
+            boinc_msg_prefix(buf, sizeof(buf)), retval
         );
         exit(1);
     }
@@ -227,7 +227,7 @@ int main(int argc, char * argv[]) {
                 retval = do_checkpoint(out, NUM_ITERATIONS, input, matrixSize);
                 if (retval) {
                     fprintf(stderr, "%s APP: maxtrix_inversion checkpoint failed %d\n",
-                        boinc_msg_prefix(buf), retval
+                        boinc_msg_prefix(buf, sizeof(buf)), retval
                     );
                     exit(1);
                 }
diff --git a/samples/example_app/uc2.cpp b/samples/example_app/uc2.cpp
index 2344d4b0ec..320adad20d 100755
--- a/samples/example_app/uc2.cpp
+++ b/samples/example_app/uc2.cpp
@@ -151,7 +151,7 @@ int main(int argc, char **argv) {
     retval = boinc_init();
     if (retval) {
         fprintf(stderr, "%s boinc_init returned %d\n",
-            boinc_msg_prefix(buf), retval
+            boinc_msg_prefix(buf, sizeof(buf)), retval
         );
         exit(retval);
     }
@@ -163,7 +163,7 @@ int main(int argc, char **argv) {
     if (!infile) {
         fprintf(stderr,
             "%s Couldn't find input file, resolved name %s.\n",
-            boinc_msg_prefix(buf), input_path
+            boinc_msg_prefix(buf, sizeof(buf)), input_path
         );
         exit(-1);
     }
@@ -192,10 +192,10 @@ int main(int argc, char **argv) {
     }
     if (retval) {
         fprintf(stderr, "%s APP: upper_case output open failed:\n",
-            boinc_msg_prefix(buf)
+            boinc_msg_prefix(buf, sizeof(buf))
         );
         fprintf(stderr, "%s resolved name %s, retval %d\n",
-            boinc_msg_prefix(buf), output_path, retval
+            boinc_msg_prefix(buf, sizeof(buf)), output_path, retval
         );
         perror("open");
         exit(1);
@@ -207,7 +207,7 @@ int main(int argc, char **argv) {
     shmem = (UC_SHMEM*)boinc_graphics_make_shmem("uppercase", sizeof(UC_SHMEM));
     if (!shmem) {
         fprintf(stderr, "%s failed to create shared mem segment\n",
-            boinc_msg_prefix(buf)
+            boinc_msg_prefix(buf, sizeof(buf))
         );
     }
     update_shmem();
@@ -243,7 +243,7 @@ int main(int argc, char **argv) {
             retval = do_checkpoint(out, nchars);
             if (retval) {
                 fprintf(stderr, "%s APP: upper_case checkpoint failed %d\n",
-                    boinc_msg_prefix(buf), retval
+                    boinc_msg_prefix(buf, sizeof(buf)), retval
                 );
                 exit(retval);
             }
@@ -258,7 +258,7 @@ int main(int argc, char **argv) {
     retval = out.flush();
     if (retval) {
         fprintf(stderr, "%s APP: upper_case flush failed %d\n",
-            boinc_msg_prefix(buf), retval
+            boinc_msg_prefix(buf, sizeof(buf)), retval
         );
         exit(1);
     }
@@ -277,7 +277,7 @@ int main(int argc, char **argv) {
                 retval = do_checkpoint(out, nchars);
                 if (retval) {
                     fprintf(stderr, "%s APP: upper_case checkpoint failed %d\n",
-                        boinc_msg_prefix(buf), retval
+                        boinc_msg_prefix(buf, sizeof(buf)), retval
                     );
                     exit(1);
                 }
diff --git a/samples/multi_thread/multi_thread.cpp b/samples/multi_thread/multi_thread.cpp
index 0c8ef4e2b1..20a16838e4 100644
--- a/samples/multi_thread/multi_thread.cpp
+++ b/samples/multi_thread/multi_thread.cpp
@@ -82,14 +82,18 @@ struct THREAD {
             NULL
         );
         if (!id) {
-            fprintf(stderr, "%s Can't start thread\n", boinc_msg_prefix(buf));
+            fprintf(stderr, "%s Can't start thread\n",
+                boinc_msg_prefix(buf, sizeof(buf))
+            );
             exit(1);
         }
 #else
         int retval;
         retval = pthread_create(&id, 0, func, (void*)this);
         if (retval) {
-            fprintf(stderr, "%s can't start thread\n", boinc_msg_prefix(buf));
+            fprintf(stderr, "%s can't start thread\n",
+                boinc_msg_prefix(buf, sizeof(buf))
+            );
             exit(1);
         }
 #endif
@@ -139,7 +143,7 @@ void* worker(void* p) {
         double x = do_a_giga_flop(i);
         t->units_done++;
         fprintf(stderr, "%s thread %d finished %d: %f\n",
-            boinc_msg_prefix(buf), t->index, i, x
+            boinc_msg_prefix(buf, sizeof(buf)), t->index, i, x
         );
     }
     t->id = THREAD_ID_NULL;
@@ -160,7 +164,7 @@ int main(int argc, char** argv) {
             nthreads = atoi(argv[++i]);
         } else {
             fprintf(stderr, "%s unrecognized arg: %s\n",
-                boinc_msg_prefix(buf), argv[i]
+                boinc_msg_prefix(buf, sizeof(buf)), argv[i]
             );
         }
     }
@@ -181,7 +185,7 @@ int main(int argc, char** argv) {
     double elapsed_time = dtime()-start_time;
     fprintf(stderr,
         "%s All done.  Used %d threads.  Elapsed time %f\n",
-        boinc_msg_prefix(buf), nthreads, elapsed_time
+        boinc_msg_prefix(buf, sizeof(buf)), nthreads, elapsed_time
     );
     boinc_finish(0);
 }
diff --git a/samples/nvcuda/cuda.cpp b/samples/nvcuda/cuda.cpp
index 520f3005ca..078af4bd52 100644
--- a/samples/nvcuda/cuda.cpp
+++ b/samples/nvcuda/cuda.cpp
@@ -44,8 +44,7 @@ bool early_crash = false;
 bool early_sleep = false;
 double cpu_time = 20, comp_result;
 
-int main(int argc, char** argv)
-{
+int main(int argc, char** argv) {
     int i, retval, lastInversion=0, checkpointExists=0, dimension=0;
     double fd;
     char input_path[512], output_path[512], chkpt_path[512], buf[256];
@@ -68,9 +67,10 @@ int main(int argc, char** argv)
 	
     retval = boinc_init();
     if (retval) {
-        fprintf(stderr, "%s boinc_init returned %d\n",
-				boinc_msg_prefix(buf), retval
-				);
+        fprintf(stderr,
+            "%s boinc_init returned %d\n",
+            boinc_msg_prefix(buf, sizeof(buf)), retval
+        );
         exit(retval);
     }
     
@@ -80,9 +80,9 @@ int main(int argc, char** argv)
     infile = boinc_fopen(input_path, "r");
     if (!infile) {
         fprintf(stderr,
-				"%s Couldn't find input file, resolved name %s.\n",
-				boinc_msg_prefix(buf), input_path
-				);
+            "%s Couldn't find input file, resolved name %s.\n",
+            boinc_msg_prefix(buf, sizeof(buf)), input_path
+        );
         getchar();
         exit(-1);
     }
@@ -113,12 +113,14 @@ int main(int argc, char** argv)
     retval = out.open(output_path, "wb");
     
     if (retval) {
-        fprintf(stderr, "%s APP: matrix_inversion output open failed:\n",
-                boinc_msg_prefix(buf)
-                );
-        fprintf(stderr, "%s resolved name %s, retval %d\n",
-                boinc_msg_prefix(buf), output_path, retval
-                );
+        fprintf(stderr,
+            "%s APP: matrix_inversion output open failed:\n",
+            boinc_msg_prefix(buf, sizeof(buf))
+        );
+        fprintf(stderr,
+            "%s resolved name %s, retval %d\n",
+            boinc_msg_prefix(buf, sizeof(buf)), output_path, retval
+        );
         perror("open");
         exit(1);
     }
@@ -128,9 +130,10 @@ int main(int argc, char** argv)
     //
     shmem = (UC_SHMEM*)boinc_graphics_make_shmem("matrix_inversion", sizeof(UC_SHMEM));
     if (!shmem) {
-        fprintf(stderr, "%s failed to create shared mem segment\n",
-                boinc_msg_prefix(buf)
-                );
+        fprintf(stderr,
+            "%s failed to create shared mem segment\n",
+            boinc_msg_prefix(buf, sizeof(buf))
+        );
     }
     update_shmem();
     boinc_register_timer_callback(update_shmem);
@@ -175,9 +178,10 @@ int main(int argc, char** argv)
             //we'll need to write the current matrix to the state file.
             retval = do_checkpoint(out, i, h_idata, dimension); 
             if (retval) {
-                fprintf(stderr, "%s APP: matrix_inversion checkpoint failed %d\n",
-                        boinc_msg_prefix(buf), retval
-                        );
+                fprintf(stderr,
+                    "%s APP: matrix_inversion checkpoint failed %d\n",
+                    boinc_msg_prefix(buf, sizeof(buf)), retval
+                );
                 exit(retval);
             }
             boinc_checkpoint_completed();
@@ -194,9 +198,10 @@ int main(int argc, char** argv)
     cudaFreeHost( h_idata );
     retval = out.flush(); //force the output file to be closed.
     if (retval) {
-        fprintf(stderr, "%s APP: matrix_inversion flush failed %d\n",
-                boinc_msg_prefix(buf), retval
-                );
+        fprintf(stderr,
+            "%s APP: matrix_inversion flush failed %d\n",
+            boinc_msg_prefix(buf, sizeof(buf)), retval
+        );
         exit(1);
     }
 
@@ -214,9 +219,10 @@ int main(int argc, char** argv)
             if (boinc_time_to_checkpoint()) {
                 retval = do_checkpoint(out, NUM_ITERATIONS, h_idata, dimension);
                 if (retval) {
-                    fprintf(stderr, "%s APP: maxtrix_inversion checkpoint failed %d\n",
-							boinc_msg_prefix(buf), retval
-							);
+                    fprintf(stderr,
+                        "%s APP: maxtrix_inversion checkpoint failed %d\n",
+                        boinc_msg_prefix(buf, sizeof(buf)), retval
+                    );
                     exit(1);
                 }
                 boinc_checkpoint_completed();
@@ -381,4 +387,4 @@ void print_to_file(MFILE *out, float *h_odata, int dimension) {
         }
         --num_elements;
     }
-}
\ No newline at end of file
+}
diff --git a/samples/nvopencl/nvopencl.cpp b/samples/nvopencl/nvopencl.cpp
index 9ce7bd7dec..243172c1b7 100644
--- a/samples/nvopencl/nvopencl.cpp
+++ b/samples/nvopencl/nvopencl.cpp
@@ -57,8 +57,10 @@ int main(int argc, char * argv[]) {
 	
     retval = boinc_init();
     if (retval) {
-        fprintf(stderr, "%s boinc_init returned %d\n",
-                boinc_msg_prefix(buf), retval );
+        fprintf(stderr,
+            "%s boinc_init returned %d\n",
+            boinc_msg_prefix(buf, sizeof(buf)), retval
+        );
         exit(retval);
     }
     
@@ -69,7 +71,7 @@ int main(int argc, char * argv[]) {
     if (!infile) {
         fprintf(stderr,
             "%s Couldn't find input file in boinc\\win_build, resolved name %s.\n",
-            boinc_msg_prefix(buf), input_path
+            boinc_msg_prefix(buf, sizeof(buf)), input_path
         );
         getchar();
         exit(-1);
@@ -101,11 +103,13 @@ int main(int argc, char * argv[]) {
     retval = out.open(output_path, "wb");
 
     if (retval) {
-        fprintf(stderr, "%s APP: matrix_inversion output open failed:\n",
-            boinc_msg_prefix(buf)
+        fprintf(stderr,
+            "%s APP: matrix_inversion output open failed:\n",
+            boinc_msg_prefix(buf, sizeof(buf))
         );
-        fprintf(stderr, "%s resolved name %s, retval %d\n",
-            boinc_msg_prefix(buf), output_path, retval
+        fprintf(stderr,
+            "%s resolved name %s, retval %d\n",
+            boinc_msg_prefix(buf, sizeof(buf)), output_path, retval
         );
         perror("open");
         exit(1);
@@ -116,8 +120,9 @@ int main(int argc, char * argv[]) {
     //
     shmem = (UC_SHMEM*)boinc_graphics_make_shmem("matrix_inversion", sizeof(UC_SHMEM));
     if (!shmem) {
-        fprintf(stderr, "%s failed to create shared mem segment\n",
-            boinc_msg_prefix(buf)
+        fprintf(stderr,
+            "%s failed to create shared mem segment\n",
+            boinc_msg_prefix(buf, sizeof(buf))
         );
     }
     update_shmem();
@@ -179,8 +184,9 @@ int main(int argc, char * argv[]) {
             //we'll need to write the current matrix to the state file.
             retval = do_checkpoint(out, i, input, matrixSize); 
             if (retval) {
-                fprintf(stderr, "%s APP: matrix_inversion checkpoint failed %d\n",
-                    boinc_msg_prefix(buf), retval
+                fprintf(stderr,
+                    "%s APP: matrix_inversion checkpoint failed %d\n",
+                    boinc_msg_prefix(buf, sizeof(buf)), retval
                 );
                 exit(retval);
             }
@@ -197,8 +203,9 @@ int main(int argc, char * argv[]) {
 
     retval = out.flush(); //force the output file to be closed.
     if (retval) {
-        fprintf(stderr, "%s APP: matrix_inversion flush failed %d\n",
-            boinc_msg_prefix(buf), retval
+        fprintf(stderr,
+            "%s APP: matrix_inversion flush failed %d\n",
+            boinc_msg_prefix(buf, sizeof(buf)), retval
         );
         exit(1);
     }
@@ -226,8 +233,9 @@ int main(int argc, char * argv[]) {
             if (boinc_time_to_checkpoint()) {
                 retval = do_checkpoint(out, NUM_ITERATIONS, input, matrixSize);
                 if (retval) {
-                    fprintf(stderr, "%s APP: maxtrix_inversion checkpoint failed %d\n",
-                        boinc_msg_prefix(buf), retval
+                    fprintf(stderr,
+                        "%s APP: maxtrix_inversion checkpoint failed %d\n",
+                        boinc_msg_prefix(buf, sizeof(buf)), retval
                     );
                     exit(1);
                 }
diff --git a/samples/wrapper/wrapper.cpp b/samples/wrapper/wrapper.cpp
index 96713a47c8..fdd2db9acb 100644
--- a/samples/wrapper/wrapper.cpp
+++ b/samples/wrapper/wrapper.cpp
@@ -135,7 +135,7 @@ int TASK::parse(XML_PARSER& xp) {
     while (!xp.get(tag, sizeof(tag), is_tag)) {
         if (!is_tag) {
             fprintf(stderr, "%s TASK::parse(): unexpected text %s\n",
-                boinc_msg_prefix(buf), tag
+                boinc_msg_prefix(buf, sizeof(buf)), tag
             );
             continue;
         }
@@ -172,7 +172,10 @@ int parse_job_file() {
     boinc_resolve_filename(JOB_FILENAME, buf, 1024);
     FILE* f = boinc_fopen(buf, "r");
     if (!f) {
-        fprintf(stderr, "%s can't open job file %s\n", boinc_msg_prefix(buf2), buf);
+        fprintf(stderr,
+            "%s can't open job file %s\n",
+            boinc_msg_prefix(buf2, sizeof(buf2)), buf
+        );
         return ERR_FOPEN;
     }
     mf.init_file(f);
@@ -181,8 +184,9 @@ int parse_job_file() {
     if (!xp.parse_start("job_desc")) return ERR_XML_PARSE;
     while (!xp.get(tag, sizeof(tag), is_tag)) {
         if (!is_tag) {
-            fprintf(stderr, "%s SCHED_CONFIG::parse(): unexpected text %s\n",
-                boinc_msg_prefix(buf2), tag
+            fprintf(stderr,
+                "%s SCHED_CONFIG::parse(): unexpected text %s\n",
+                boinc_msg_prefix(buf2, sizeof(buf2)), tag
             );
             continue;
         }
@@ -283,7 +287,7 @@ int TASK::run(int argct, char** argvt) {
     }
 
     fprintf(stderr, "%s wrapper: running %s (%s)\n",
-        boinc_msg_prefix(buf), app_path, command_line.c_str()
+        boinc_msg_prefix(buf, sizeof(buf)), app_path, command_line.c_str()
     );
 
 #ifdef _WIN32