diff --git a/ares/m4/reentrant.m4 b/ares/m4/reentrant.m4
index bfe68cb40633a132e50ad681319ceaa460ed7bcd..3569f0e3c2ff90cdbee4ead013ec0a196cfa82a1 100644
--- a/ares/m4/reentrant.m4
+++ b/ares/m4/reentrant.m4
@@ -354,9 +354,9 @@ AC_DEFUN([CARES_CONFIGURE_FROM_NOW_ON_WITH_REENTRANT], [
 AC_DEFINE(NEED_REENTRANT, 1,
   [Define to 1 if _REENTRANT preprocessor symbol must be defined.])
 cat >>confdefs.h <<_ACEOF
-[#ifndef _REENTRANT
+#ifndef _REENTRANT
 # define _REENTRANT
-#endif]
+#endif
 _ACEOF
 ])
 
diff --git a/m4/reentrant.m4 b/m4/reentrant.m4
index e5af41e97cf6b78513dd87041be41a1772ee4ed5..1b47308d2a998d972f3e53abde4cab7ae96449d3 100644
--- a/m4/reentrant.m4
+++ b/m4/reentrant.m4
@@ -376,9 +376,9 @@ AC_DEFUN([CURL_CONFIGURE_FROM_NOW_ON_WITH_REENTRANT], [
 AC_DEFINE(NEED_REENTRANT, 1,
   [Define to 1 if _REENTRANT preprocessor symbol must be defined.])
 cat >>confdefs.h <<_ACEOF
-[#ifndef _REENTRANT
+#ifndef _REENTRANT
 # define _REENTRANT
-#endif]
+#endif
 _ACEOF
 ])