diff --git a/nemo_rl/environments/nemo_gym.py b/nemo_rl/environments/nemo_gym.py
index 30fb04954b2..1b3daba4612 100644
--- a/nemo_rl/environments/nemo_gym.py
+++ b/nemo_rl/environments/nemo_gym.py
@@ -417,6 +417,13 @@ def _postprocess_nemo_gym_to_nemo_rl_result(
                     "with enable_return_routed_experts."
                 )
 
+            # The next prompt prefill supplies the real route for the previous
+            # turn's final token, whose decode route was padded.
+            if routed_experts is not None and seen_token_ids:
+                previous_routes = nemo_rl_message_log[-1].get("routed_experts")
+                if isinstance(previous_routes, torch.Tensor):
+                    previous_routes[-1] = routed_experts[len(seen_token_ids) - 1]
+
             prompt_start = len(seen_token_ids)
             prompt_end = len(prompt_token_ids)
             generation_start = prompt_end
diff --git a/tests/unit/environments/test_nemo_gym_router_replay.py b/tests/unit/environments/test_nemo_gym_router_replay.py
index d1171856213..15383d8af5b 100644
--- a/tests/unit/environments/test_nemo_gym_router_replay.py
+++ b/tests/unit/environments/test_nemo_gym_router_replay.py
@@ -27,6 +27,10 @@ def _routes(num_tokens: int) -> list[list[list[int]]]:
 
 
 def test_nemo_gym_postprocess_slices_routed_experts():
+    first_turn_routes = _routes(3)
+    first_turn_routes[-1] = [[0, 1]]
+    second_turn_routes = _routes(7)
+    second_turn_routes[2] = [[30, 31]]
     nemo_gym_result = {
         "response": {
             "output": [
@@ -34,13 +38,13 @@ def test_nemo_gym_postprocess_slices_routed_experts():
                     "prompt_token_ids": [1, 2],
                     "generation_token_ids": [3],
                     "generation_log_probs": [-0.1],
-                    "routed_experts": _routes(3),
+                    "routed_experts": first_turn_routes,
                 },
                 {
                     "prompt_token_ids": [1, 2, 3, 4, 5],
                     "generation_token_ids": [6, 7],
                     "generation_log_probs": [-0.2, -0.3],
-                    "routed_experts": _routes(7),
+                    "routed_experts": second_turn_routes,
                 },
             ]
         },
@@ -58,13 +62,13 @@ class _MockSelf:
 
     message_log = result["message_log"]
     assert message_log[0]["token_ids"].tolist() == [1, 2]
-    assert message_log[0]["routed_experts"].tolist() == _routes(2)
+    assert message_log[0]["routed_experts"].tolist() == first_turn_routes[:2]
     assert message_log[1]["token_ids"].tolist() == [3]
-    assert message_log[1]["routed_experts"].tolist() == _routes(3)[2:3]
+    assert message_log[1]["routed_experts"].tolist() == second_turn_routes[2:3]
     assert message_log[2]["token_ids"].tolist() == [4, 5]
-    assert message_log[2]["routed_experts"].tolist() == _routes(7)[3:5]
+    assert message_log[2]["routed_experts"].tolist() == second_turn_routes[3:5]
     assert message_log[3]["token_ids"].tolist() == [6, 7]
-    assert message_log[3]["routed_experts"].tolist() == _routes(7)[5:7]
+    assert message_log[3]["routed_experts"].tolist() == second_turn_routes[5:7]
 
 
 def test_nemo_gym_postprocess_requires_routed_experts_when_configured():