diff --git a/lasso/xml/tools.c b/lasso/xml/tools.c
index 385858d1..bbc87d9f 100644
--- a/lasso/xml/tools.c
+++ b/lasso/xml/tools.c
@@ -47,6 +47,7 @@
#include <libxml/xmlIO.h>
#include <openssl/evp.h>
+#include <openssl/pem.h>
#include <xmlsec/base64.h>
#include <xmlsec/crypto.h>