diff --git a/lib/libc/gen/sysctlnametomib.c b/lib/libc/gen/sysctlnametomib.c
index b84bafeedf26..1515784a5bec 100644
--- a/lib/libc/gen/sysctlnametomib.c
+++ b/lib/libc/gen/sysctlnametomib.c
@@ -29,6 +29,7 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/types.h>
 #include <sys/sysctl.h>
+#include <string.h>
 
 /*
  * This function uses a presently undocumented interface to the kernel