diff --git a/configure.ac b/configure.ac
index 2a2edeb..c84c6c7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -339,6 +339,7 @@ ACX_PTHREAD(
 #
 echo "----------------------- pthread_rwlock_t stuff --------------------------------"
 AC_MSG_CHECKING([if pthread_rwlock_t is available])
+AC_LANG([C])
 AC_COMPILE_IFELSE(
 	[AC_LANG_PROGRAM(
 		[#include <pthread.h>],