diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
index f21184a78fd..da0d3db5c66 100644
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -132,6 +132,10 @@ newcompobject(PyTypeObject *type)
     }
 #ifdef WITH_THREAD
     self->lock = PyThread_allocate_lock();
+    if (self->lock == NULL) {
+        PyErr_SetString(PyExc_MemoryError, "Unable to allocate lock");
+        return NULL;
+    }
 #endif
     return self;
 }