diff --git a/reference-implementation/include/emitc/tosa.h b/reference-implementation/include/emitc/tosa.h
index 12d5e955..2019dfba 100644
--- a/reference-implementation/include/emitc/tosa.h
+++ b/reference-implementation/include/emitc/tosa.h
@@ -217,7 +217,7 @@ inline Src minimum(Src x, Src y) {
 }
 
 template <typename Src, IsTensorOfType<Src, int32_t> = true>
-inline Src mul(Src x, Src y, const int32_t shift) {
+inline Src mul(Src x, Src y, const int8_t shift) {
   // Adopted from
   // https://git.mlplatform.org/tosa/reference_model.git/tree/reference_model/src/ops/ewise_binary.cc?id=df8626976df6c779bb30df9c5ceef689462109c0#n436
   if (shift > 0) {
diff --git a/reference-implementation/unittests/tosa.cpp b/reference-implementation/unittests/tosa.cpp
index 4724e48e..8f0a148a 100644
--- a/reference-implementation/unittests/tosa.cpp
+++ b/reference-implementation/unittests/tosa.cpp
@@ -552,7 +552,7 @@ TEST(tosa, mul) {
   Tensor2D<int32_t, 2, 2> t2{1, 2, 3, 4};
 
   auto lambda_1d_int_shift = [&s2, &t2]() -> Tensor2D<int32_t, 2, 2> {
-    int32_t shift{2};
+    int8_t shift{2};
     return tosa::mul(s2, t2, shift);
   };