diff --git a/driver/others/blas_server.c b/driver/others/blas_server.c
index 051513f27..a8a84acbb 100644
--- a/driver/others/blas_server.c
+++ b/driver/others/blas_server.c
@@ -973,7 +973,7 @@ void goto_set_num_threads(int num_threads) {
 
     increased_threads = 1;
 
-    for(i = blas_num_threads - 1; i < num_threads - 1; i++){
+    for(i = (blas_num_threads > 0) ? blas_num_threads - 1 : 0; i < num_threads - 1; i++){
 
       atomic_store_queue(&thread_status[i].queue, (blas_queue_t *)0);
       thread_status[i].status = THREAD_STATUS_WAKEUP;
diff --git a/driver/others/blas_server_win32.c b/driver/others/blas_server_win32.c
index afa33cccc..5bdfc1276 100644
--- a/driver/others/blas_server_win32.c
+++ b/driver/others/blas_server_win32.c
@@ -568,7 +568,7 @@ void goto_set_num_threads(int num_threads)
 			blas_server_avail = 1;
 		}
 
-		for(i = blas_num_threads - 1; i < num_threads - 1; i++){
+		for(i = (blas_num_threads > 0) ? blas_num_threads - 1 : 0; i < num_threads - 1; i++){
 
 			blas_threads[i] = CreateThread(NULL, 0,
 				     blas_thread_server, (void *)i,