diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 6dabd34..4a8686c 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1848,7 +1848,7 @@
 {
     unsigned char *p = ssl->handshake->premaster;
     unsigned char *end = p + sizeof( ssl->handshake->premaster );
-    const unsigned char *psk;
+    const unsigned char *psk = NULL;
     size_t psk_len = 0;
 
     if( mbedtls_ssl_get_psk( ssl, &psk, &psk_len )