diff --git a/libfreerdp/core/certificate.c b/libfreerdp/core/certificate.c
index 1d93f6c6a..e2d5c3a4e 100644
--- a/libfreerdp/core/certificate.c
+++ b/libfreerdp/core/certificate.c
@@ -753,7 +753,7 @@ rdpRsaKey* key_new(const char* keyfile)
 	char* buffer = NULL;
 	rdpRsaKey* key = NULL;
 
-	fp = fopen(keyfile, "r+b");
+	fp = fopen(keyfile, "rb");
 	if (!fp)
 	{
 		WLog_ERR(TAG, "unable to open RSA key file %s: %s.", keyfile, strerror(errno));