diff --git a/shim.h b/shim.h
index e1430f7..9991cd0 100644
--- a/shim.h
+++ b/shim.h
@@ -22,6 +22,7 @@
 #include <openssl/md4.h>
 #include <openssl/md5.h>
 #include <openssl/sha.h>
+#include <openssl/rsa.h>
 #include <openssl/hmac.h>
 #include <openssl/rand.h>