diff --git a/libs/pbd/wscript b/libs/pbd/wscript
index 06b285c79d..df92345d40 100644
--- a/libs/pbd/wscript
+++ b/libs/pbd/wscript
@@ -115,7 +115,7 @@ def configure(conf):
             define_name='HAVE_GETMNTENT', execute = False, mandatory=False)
     conf.check_cc(
             msg="Checking for function 'localtime_r' in time.h",
-            fragment = "#include <time.h>\n int main(void) { return localtime_r(NULL, NULL); }\n",
+            fragment = "#include <time.h>\n int main(void) { return NULL == localtime_r(NULL, NULL); }\n",
             define_name='HAVE_LOCALTIME_R', execute = False, mandatory=False)
 
     # Boost headers