diff --git a/source/tls_channel_handler.c b/source/tls_channel_handler.c
index aa80459b7..83955def1 100644
--- a/source/tls_channel_handler.c
+++ b/source/tls_channel_handler.c
@@ -441,6 +441,8 @@ int aws_tls_ctx_options_init_default_server(
 }
 
 int aws_tls_ctx_options_set_alpn_list(struct aws_tls_ctx_options *options, const char *alpn_list) {
+    aws_string_destroy(options->alpn_list);
+
     options->alpn_list = aws_string_new_from_c_str(options->allocator, alpn_list);
     if (!options->alpn_list) {
         return AWS_OP_ERR;