diff --git a/config.h.in b/config.h.in
index 9e5f18319..6f6712fc4 100644
--- a/config.h.in
+++ b/config.h.in
@@ -146,6 +146,7 @@
 #undef  HAVE_ASINH
 #undef  HAVE_ATANH
 #undef  HAVE_CHDIR
+#undef  HAVE_CTIME
 #undef  HAVE_DLOPEN
 #undef  HAVE_DUP2
 #undef  HAVE_FESETTRAPENABLE