--- a/configure.ac
+++ b/configure.ac
@@ -2877,6 +2877,7 @@ CURL_VERIFY_RUNTIMELIBS
AC_CHECK_SIZEOF(size_t)
AC_CHECK_SIZEOF(long)
+AC_CHECK_SIZEOF(long long)
AC_CHECK_SIZEOF(int)
AC_CHECK_SIZEOF(short)
CURL_CONFIGURE_LONG