diff --git a/sys/src/cmd/paint.c b/sys/src/cmd/paint.c
index 1e4d95d47..ab361e7f9 100644
--- a/sys/src/cmd/paint.c
+++ b/sys/src/cmd/paint.c
@@ -86,7 +86,7 @@ main(int argc, char *argv[])
 	case 0:
 		break;
 	case 1:
-		strncpy(file, argv[0], sizeof(argv[0]));
+		strncpy(file, argv[0], sizeof(file)-1);
 		if(loadimg(file) < 0)
 			sysfatal("%r");
 		break;