diff --git a/src/cf/have-struct-field.m4 b/src/cf/have-struct-field.m4
index 36f75c9899..98a976b8b5 100644
--- a/src/cf/have-struct-field.m4
+++ b/src/cf/have-struct-field.m4
@@ -4,7 +4,9 @@ dnl should be shipping AC_ macros.
 AC_DEFUN([OPENAFS_HAVE_STRUCT_FIELD], [
 define(cache_val, translit(ac_cv_type_$1_$2, [A-Z ], [a-z_]))
 AC_CACHE_CHECK([for $2 in $1], cache_val,[
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[$3]],
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+        $3
+        #include <string.h>]],
         [[$1 x; memset(&x, 0, sizeof(x)); x.$2]])],
         [cache_val=yes],
         [cache_val=no])