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