diff --git a/config-post.h b/config-post.h
index 063e30fa37..24117bbbd4 100644
--- a/config-post.h
+++ b/config-post.h
@@ -36,6 +36,7 @@
 # undef WITH_DEVMAPPER
 # undef WITH_DTRACE_PROBES
 # undef WITH_GNUTLS
+# undef WITH_JANSSON
 # undef WITH_LIBSSH
 # undef WITH_MACVTAP
 # undef WITH_NUMACTL