diff --git a/libc/strtod.c b/libc/strtod.c
index a48abe5..f3b1637 100644
--- a/libc/strtod.c
+++ b/libc/strtod.c
@@ -1,5 +1,6 @@
 #include <u.h>
 #include <libc.h>
+#include <ctype.h>
 #include "fmtdef.h"
 
 static ulong