diff --git a/include/plan9/libc.h b/include/plan9/libc.h
index 0870a5b4af..e6f9839c8e 100644
--- a/include/plan9/libc.h
+++ b/include/plan9/libc.h
@@ -2,7 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+#define Runemax Plan9Runemax
 #include "/sys/include/libc.h"
+#undef Runemax
 #include "/sys/include/ctype.h"
 
 enum