diff --git a/lib/py/src/ext/protocol.tcc b/lib/py/src/ext/protocol.tcc
index e15df7e..ede2bb4 100644
--- a/lib/py/src/ext/protocol.tcc
+++ b/lib/py/src/ext/protocol.tcc
@@ -174,7 +174,7 @@
   if (output_->buf.capacity() < need) {
     try {
       output_->buf.reserve(need);
-    } catch (std::bad_alloc& ex) {
+    } catch (std::bad_alloc&) {
       PyErr_SetString(PyExc_MemoryError, "Failed to allocate write buffer");
       return false;
     }