diff --git a/dir.c b/dir.c
index e983ea2552..a9435f68cf 100644
--- a/dir.c
+++ b/dir.c
@@ -1081,7 +1081,7 @@ dir_s_rmdir(VALUE obj, VALUE dir)
 static VALUE
 sys_warning_1(VALUE mesg)
 {
-    rb_sys_warning("%s:%s", strerror(errno), (const char *)mesg);
+    rb_sys_warning("%s", (const char *)mesg);
     return Qnil;
 }
 
diff --git a/error.c b/error.c
index 0e8e17b195..662c6d4bee 100644
--- a/error.c
+++ b/error.c
@@ -2096,7 +2096,6 @@ rb_sys_warning(const char *fmt, ...)
 
     if (!RTEST(ruby_verbose)) return;
 
-    snprintf(buf, BUFSIZ, "warning: %s", fmt);
     snprintf(buf+strlen(buf), BUFSIZ-strlen(buf), ": %s", strerror(errno_save));
 
     va_start(args, fmt);