--- aclocal.m4
+++ aclocal.m4
@@ -26,7 +26,7 @@
 AC_TRY_LINK(dnl
 ifelse([$2], [main], , dnl Avoid conflicting decl of main.
 [/* Override any gcc2 internal prototype to avoid an error.  */
-]ifelse(AC_LANG, CPLUSPLUS, [#ifdef __cplusplus
+]ifelse([AC_LANG], CPLUSPLUS, [#ifdef __cplusplus
 extern "C"
 #endif
 ])dnl