diff --git a/synth/validator/moving_average.py b/synth/validator/moving_average.py
index 168d3e96..5f27ec74 100644
--- a/synth/validator/moving_average.py
+++ b/synth/validator/moving_average.py
@@ -126,6 +126,24 @@ def apply_per_asset_coefficients(
     return df["prompt_score_v3"]
 
 
+def _replace_inf_rolling_avgs(rolling_avg_data: list[dict]) -> None:
+    """Replace inf rolling averages with the worst finite value.
+
+    Inf causes NaN weights when all miners have inf
+    (inf - inf = nan in softmax).
+    """
+    finite_avgs = [
+        r["rolling_avg"]
+        for r in rolling_avg_data
+        if np.isfinite(r["rolling_avg"])
+    ]
+    if finite_avgs:
+        worst_finite = max(finite_avgs)
+        for r in rolling_avg_data:
+            if not np.isfinite(r["rolling_avg"]):
+                r["rolling_avg"] = worst_finite
+
+
 def compute_smoothed_score(
     miner_data_handler: MinerDataHandler,
     input_df: DataFrame,
@@ -167,6 +185,8 @@ def compute_smoothed_score(
             {"miner_id": miner_id, "rolling_avg": rolling_avg}
         )
 
+    _replace_inf_rolling_avgs(rolling_avg_data)
+
     # Add the miner UID to the results
     moving_averages_data = miner_data_handler.populate_miner_uid_in_miner_data(
         rolling_avg_data
diff --git a/tests/test_calculate_crps.py b/tests/test_calculate_crps.py
index 5376db06..64d3ee72 100644
--- a/tests/test_calculate_crps.py
+++ b/tests/test_calculate_crps.py
@@ -481,3 +481,31 @@ def test_high_freq_gap_intervals_produce_different_scores(self):
         self.assertEqual(len(gap_increments), 1)  # gap: 1 evaluation
         self.assertEqual(len(reg_increments), 6)  # regular: 6 evaluations
         self.assertNotEqual(score_gap, score_reg)
+
+
+class TestSoftmaxWithInf(unittest.TestCase):
+    """Tests for compute_softmax handling of inf values."""
+
+    def test_softmax_single_inf_gives_zero_weight(self):
+        """A single inf score should get 0 weight."""
+        scores = np.array([50, 60, 70, np.inf])
+        weights = compute_softmax(scores, -0.2)
+        self.assertTrue(np.all(np.isfinite(weights)))
+        self.assertAlmostEqual(weights.sum(), 1.0, places=6)
+        self.assertEqual(weights[-1], 0.0)
+
+    def test_softmax_all_inf_produces_nan(self):
+        """All-inf input produces NaN weights (the bug)."""
+        scores = np.array([np.inf, np.inf, np.inf])
+        weights = compute_softmax(scores, -0.2)
+        # This proves the bug: all NaN weights
+        self.assertTrue(np.all(np.isnan(weights)))
+
+    def test_softmax_all_finite_works(self):
+        """Normal finite scores produce valid weights."""
+        scores = np.array([50, 60, 70, 80])
+        weights = compute_softmax(scores, -0.2)
+        self.assertTrue(np.all(np.isfinite(weights)))
+        self.assertAlmostEqual(weights.sum(), 1.0, places=6)
+        # Lower score = better = higher weight (beta < 0)
+        self.assertGreater(weights[0], weights[-1])