diff --git a/library/gcm.c b/library/gcm.c
index f4f735b..b537b02 100644
--- a/library/gcm.c
+++ b/library/gcm.c
@@ -168,6 +168,8 @@
     if( cipher_info->block_size != 16 )
         return( POLARSSL_ERR_GCM_BAD_INPUT );
 
+    cipher_free( &ctx->cipher_ctx );
+
     if( ( ret = cipher_init_ctx( &ctx->cipher_ctx, cipher_info ) ) != 0 )
         return( ret );