diff --git a/qemu-nbd.c b/qemu-nbd.c
index 91ea01414d..6707ea5cac 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -353,7 +353,8 @@ int main(int argc, char **argv)
         }
 
         if (socket == NULL) {
-            sprintf(sockpath, SOCKET_PATH, basename(device));
+            snprintf(sockpath, sizeof(sockpath), SOCKET_PATH,
+                     basename(device));
             socket = sockpath;
         }