diff --git a/evalharness/model/adapter.py b/evalharness/model/adapter.py
index 3b17c16..feebd20 100644
--- a/evalharness/model/adapter.py
+++ b/evalharness/model/adapter.py
@@ -481,7 +481,9 @@ class OpenAICompatible(ModelAdapter):
             # read timeout scales with the generation budget: a 32k-token
             # CoT legitimately takes 10+ minutes; a fixed 300s timeout would
             # kill and retry it forever (looks like a hang)
-            _rt = max(self.extra.get('timeout', 300),
+            # generous: GLM gateway takes 30+ seconds to start responding
+            # on 100k+ token inputs, even before any generation begins
+            _rt = max(self.extra.get('timeout', 600),
                       int(payload.get('max_tokens') or 0) * 0.15)
             async with httpx.AsyncClient(timeout=httpx.Timeout(
                 connect=self.extra.get('connect_timeout', 15),