diff --git a/test/python/ext/ep/test_internode_multirank.py b/test/python/ext/ep/test_internode_multirank.py
index 901a67a7..eddfb6be 100644
--- a/test/python/ext/ep/test_internode_multirank.py
+++ b/test/python/ext/ep/test_internode_multirank.py
@@ -259,7 +259,10 @@ def main():
     diff = (got - expected).abs().max().item()
     max_exp = expected.abs().max().item()
     print(f"[combine r{rank}] max|got-expected|={diff:.4e} max|expected|={max_exp:.4e}", flush=True)
-    assert diff < 1e-2, f"rank{rank}: combine mismatch max diff {diff}"
+    # bf16 accumulator has 7-bit mantissa; intermediate partial sums can
+    # round at ulp = max_exp * 2**-7. Use a tolerance that scales with magnitude.
+    tol = max(1e-2, max_exp * (1.0 / 64))
+    assert diff <= tol, f"rank{rank}: combine mismatch max diff {diff} > tol {tol} (max_exp={max_exp})"
 
     dist.barrier(group=group)
     if rank == 0: