diff --git a/lib/shmem.C b/lib/shmem.C
index d08a9c4dc9..3683ecac65 100755
--- a/lib/shmem.C
+++ b/lib/shmem.C
@@ -48,7 +48,7 @@ extern "C" int debug_printf(const char *fmt, ...);
 #endif
 #endif
 
-#ifdef USE_FILE_MAPPED_SHMEM
+#if(!defined (_WIN32) && !defined (__EMX__))
 #include <fcntl.h>
 #include <unistd.h>
 #include <sys/stat.h>
@@ -165,10 +165,9 @@ int detach_shmem(void* p) {
 }
 
 #else
+// V6 mmap() shared memory for Unix/Linux/Mac
 
-#ifdef USE_FILE_MAPPED_SHMEM
-
-int create_shmem(char *path, size_t size, void** pp) {
+int create_shmem_mmap(char *path, size_t size, void** pp) {
     int fd, retval;
     struct stat sbuf;
     
@@ -210,11 +209,11 @@ int create_shmem(char *path, size_t size, void** pp) {
     return 0;
 }
 
-int destroy_shmem(key_t key){
+int destroy_shmem_mmap(key_t key){
     return 0;
 }
 
-int attach_shmem(char *path, void** pp) {
+int attach_shmem_mmap(char *path, void** pp) {
     int fd, retval;
     struct stat sbuf;
     
@@ -241,12 +240,12 @@ int attach_shmem(char *path, void** pp) {
 }
 
 
-int detach_shmem(void* p, size_t size) {
+int detach_shmem_mmap(void* p, size_t size) {
     return munmap(p, size);
 }
 
-#else   // !defined(USE_FILE_MAPPED_SHMEM)
 
+// Compatibility routines for Unix/Linux/Mac V5 applications 
 int create_shmem(key_t key, int size, gid_t gid, void** pp) {
     int id;
     
@@ -360,15 +359,12 @@ int print_shmem_info(key_t key) {
     return 0;
 }
 
-#endif  // USE_FILE_MAPPED_SHMEM
-
 // For debugging shared memory logic
 // For testing on Apple, Linux, UNIX systems with limited number 
 // of shared memory segments per process and / or system-wide
 // Mac OS X has a default limit of 8 segments per process, 32 system-wide
 // If 
 void stress_shmem(short reduce_by) {
-#ifndef USE_FILE_MAPPED_SHMEM
     int retval;
     void * shmaddr[16];
     key_t key[] = {
@@ -388,7 +384,6 @@ void stress_shmem(short reduce_by) {
             retval = shmctl(id, IPC_RMID, 0);
         }
     }
-#endif  // !defined(USE_FILE_MAPPED_SHMEM)
 }
 
 #endif  // !defined(_WIN32) && !defined(__EMX__)
diff --git a/lib/shmem.h b/lib/shmem.h
index 9dfc9778da..8827a54014 100755
--- a/lib/shmem.h
+++ b/lib/shmem.h
@@ -43,24 +43,28 @@ HANDLE attach_shmem(LPCTSTR seg_name, void** pp);
 int detach_shmem(HANDLE hSharedMem, void* p);
 
 #else
-
-#ifdef USE_FILE_MAPPED_SHMEM
+#ifndef __EMX__
+// V6 mmap() shared memory for Unix/Linux/Mac
 
 #define MMAPPED_FILE_NAME    "boinc_mmap_file"
 
 // create a shared-memory segment of the given size.
 //
-extern int create_shmem(char *path, size_t size, void** pp);
+extern int create_shmem_mmap(char *path, size_t size, void** pp);
 
 // attach to a shared-memory segment
 //
-int attach_shmem(char *path, void** pp);
+int attach_shmem_mmap(char *path, void** pp);
 
 // detach from a shared-mem segment
 //
-extern int detach_shmem(void* p, size_t size);
+extern int detach_shmem_mmap(void* p, size_t size);
 
-#else
+// For testing on Apple, Linux, UNIX systems with limited number 
+// of shared memory segments per process and / or system-wide
+void stress_shmem(short reduce_by);
+
+#endif
 
 // create a shared-memory segment of the given size.
 //
@@ -76,7 +80,8 @@ extern int detach_shmem(void*);
 
 extern int shmem_info(key_t key);
 
-#endif
+#endif      // !defined(_WIN32)
+
 
 // Destroy a shared-memory segment.
 // If there are attachments to it,
@@ -84,11 +89,4 @@ extern int shmem_info(key_t key);
 //
 extern int destroy_shmem(key_t);
 
-#ifndef __EMX__
-// For testing on Apple, Linux, UNIX systems with limited number 
-// of shared memory segments per process and / or system-wide
-void stress_shmem(short reduce_by);
-#endif
-
-#endif      // !defined(_WIN32)
 #endif      // BOINC_SHMEM_H