diff --git a/samples/wrapper/wrapper.cpp b/samples/wrapper/wrapper.cpp
index 79e754b641..42ff04c68d 100644
--- a/samples/wrapper/wrapper.cpp
+++ b/samples/wrapper/wrapper.cpp
@@ -84,6 +84,7 @@ inline void debug_msg(const char* x) {
 using std::vector;
 using std::string;
 int nthreads = 1;
+int gpu_device_num = -1;
 
 struct TASK {
     string application;
@@ -233,6 +234,7 @@ void str_replace_all(char* buf, const char* s1, const char* s2) {
 // macro-substitute strings from job.xml
 // $PROJECT_DIR -> project directory
 // $NTHREADS --> --nthreads arg if present, else 1
+// $GPU_DEVICE_NUM --> gpu_device_num from init_data.xml, or --device arg
 //
 void macro_substitute(char* buf) {
     const char* pd = strlen(aid.project_dir)?aid.project_dir:".";
@@ -240,6 +242,14 @@ void macro_substitute(char* buf) {
     char nt[256];
     sprintf(nt, "%d", nthreads);
     str_replace_all(buf, "$NTHREADS", nt);
+
+    if (aid.gpu_device_num >= 0) {
+        gpu_device_num = aid.gpu_device_num;
+    }
+    if (gpu_device_num >= 0) {
+        sprintf(nt, "%d", gpu_device_num);
+        str_replace_all(buf, "$GPU_DEVICE_NUM", nt);
+    }
 }
 
 // make a list of files in the slot directory,
@@ -959,6 +969,8 @@ int main(int argc, char** argv) {
     for (int j=1; j<argc; j++) {
         if (!strcmp(argv[j], "--nthreads")) {
             nthreads = atoi(argv[++j]);
+        } else if (!strcmp(argv[j], "--device")) {
+            gpu_device_num = atoi(argv[++j]);
         }
     }