diff --git a/src/linux/err.c b/src/linux/err.c
index c291136..bc8a928 100644
--- a/src/linux/err.c
+++ b/src/linux/err.c
@@ -3,9 +3,15 @@
 #include <stdarg.h>
 #include <stdlib.h>
 
+/* basename(argv[0]) is not printed and stderr is not locked */
+
 void vwarn(const char *fmt, va_list ap)
 {
-	if (fmt) vfprintf(stderr, fmt, ap);
+	if (fmt) {
+		vfprintf(stderr, fmt, ap);
+		fputc(':', stderr);
+		fputc(' ', stderr);
+	}
 	perror("");
 }