diff --git a/acinclude.m4 b/acinclude.m4
index 8240a7da1650ed16c3a40213533dc45e007686d7..3f100a86f6371d993682fcd5c6518a3d97f33005 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -3623,7 +3623,7 @@ dnl must be recorded in curlbuild.h
 
 AC_DEFUN([CURL_CONFIGURE_LONG], [
   if test ! -z "$ac_cv_sizeof_long"; then
-    AC_MSG_WARN([AC_CHECK_SIZEOF(long) was called before CURL_CONFIGURE_LONG])
+    AC_MSG_WARN([Use CURL-CONFIGURE-LONG to check the size of long first])
   fi
   AC_MSG_CHECKING([size of long])
   curl_sizeof_long="unknown"