diff --git a/gateway/platforms/base.py b/gateway/platforms/base.py
index 8b34f461aa..5c2bbf96aa 100644
--- a/gateway/platforms/base.py
+++ b/gateway/platforms/base.py
@@ -2678,8 +2678,15 @@ class BasePlatformAdapter(ABC):
         if mode == "natural":
             min_ms, max_ms = 800, 2500
             return random.uniform(min_ms / 1000.0, max_ms / 1000.0)
-        min_ms = int(os.getenv("HERMES_HUMAN_DELAY_MIN_MS", "800"))
-        max_ms = int(os.getenv("HERMES_HUMAN_DELAY_MAX_MS", "2500"))
+        # custom mode — tolerate malformed env vars instead of crashing.
+        try:
+            min_ms = int(os.getenv("HERMES_HUMAN_DELAY_MIN_MS", "800"))
+        except (TypeError, ValueError):
+            min_ms = 800
+        try:
+            max_ms = int(os.getenv("HERMES_HUMAN_DELAY_MAX_MS", "2500"))
+        except (TypeError, ValueError):
+            max_ms = 2500
         return random.uniform(min_ms / 1000.0, max_ms / 1000.0)
 
     async def _process_message_background(self, event: MessageEvent, session_key: str) -> None:
diff --git a/tests/gateway/test_platform_base.py b/tests/gateway/test_platform_base.py
index dd6ffaf951..84f3b7239f 100644
--- a/tests/gateway/test_platform_base.py
+++ b/tests/gateway/test_platform_base.py
@@ -512,6 +512,17 @@ class TestGetHumanDelay:
             delay = BasePlatformAdapter._get_human_delay()
             assert 0.1 <= delay <= 0.2
 
+    def test_custom_mode_tolerates_malformed_env_vars(self):
+        env = {
+            "HERMES_HUMAN_DELAY_MODE": "custom",
+            "HERMES_HUMAN_DELAY_MIN_MS": "oops",
+            "HERMES_HUMAN_DELAY_MAX_MS": "still-bad",
+        }
+        with patch.dict(os.environ, env):
+            # falls back to the custom-mode defaults instead of crashing
+            delay = BasePlatformAdapter._get_human_delay()
+            assert 0.8 <= delay <= 2.5
+
 
 # ---------------------------------------------------------------------------
 # utf16_len / _prefix_within_utf16_limit / truncate_message with len_fn