diff --git a/configure.ac b/configure.ac
index 07ea81d1e..383dd2fbe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -637,7 +637,7 @@ dnl If you're seeing an error here, be sure you installed the lib/xtrans module
 dnl first and if it's not in the default location, that you set the ACLOCAL
 dnl environment variable to find it, such as:
 dnl	ACLOCAL="aclocal -I ${PREFIX}/share/aclocal"
-m4_pattern_forbid(XTRANS_CONNECTION_FLAGS)
+m4_pattern_forbid([^XTRANS_CONNECTION_FLAGS$])
 
 # Transport selection macro from xtrans.m4
 XTRANS_CONNECTION_FLAGS