diff --git a/ethosu/vela/weight_compressor.py b/ethosu/vela/weight_compressor.py
index 78c4351..db225fb 100644
--- a/ethosu/vela/weight_compressor.py
+++ b/ethosu/vela/weight_compressor.py
@@ -275,7 +275,8 @@
         quantised_scales = [(int(m), int(s)) for s, m in zip(explicit_scaling.shift, explicit_scaling.multiplier)]
     else:
         # quantise all of the weight scales into (scale_factor, shift)
-        if ifm_dtype == DataType.int16:
+        if ifm_dtype == DataType.int16 and bias_tens.dtype == DataType.int64:
+            # Reference uses reduced scaling for int16 with int64 bias
             quantised_scales = [reduced_quantise_scale(scale) for scale in scales]
         else:
             quantised_scales = [quantise_scale(scale) for scale in scales]