diff --git a/apps/spkac.c b/apps/spkac.c
index f69dc5c2612a66e5960a1b37aede5ca704228671..f3ee7e34e3a7e96dc0d61bebf89e7e63c02d9683 100644
--- a/apps/spkac.c
+++ b/apps/spkac.c
@@ -63,6 +63,7 @@
 #include <time.h>
 #include "apps.h"
 #include <openssl/bio.h>
+#include <openssl/conf.h>
 #include <openssl/err.h>
 #include <openssl/evp.h>
 #include <openssl/lhash.h>