diff --git a/src/pkcs11/openssl.c b/src/pkcs11/openssl.c
index cfbc90ac..2f5747ac 100644
--- a/src/pkcs11/openssl.c
+++ b/src/pkcs11/openssl.c
@@ -11,6 +11,7 @@
 #ifdef HAVE_OPENSSL
 #include <openssl/evp.h>
 #include <openssl/rand.h>
+#include <openssl/rsa.h>
 
 static CK_RV	sc_pkcs11_openssl_md_init(sc_pkcs11_operation_t *);
 static CK_RV	sc_pkcs11_openssl_md_update(sc_pkcs11_operation_t *,