diff --git a/ethosu/regor/architecture/ethosu55/ethos_u55_constraints.cpp b/ethosu/regor/architecture/ethosu55/ethos_u55_constraints.cpp
index da197be95af2ec642e1eaa0b5f10f9c2004792a5..55334b5afc4a6f7d8fcc06b2ef4964296d0371be 100644
--- a/ethosu/regor/architecture/ethosu55/ethos_u55_constraints.cpp
+++ b/ethosu/regor/architecture/ethosu55/ethos_u55_constraints.cpp
@@ -82,8 +82,9 @@ bool EthosU55Constraints::SupportsFusedRescale(OpType opType, TensorUsage tensor
     DataType rescaleToType, DataType opFromType, DataType opToType, const Quantization &quantization)
 {
     auto npuOp = ArchEthosU55::GetHWOp(opType);
-    bool globalScale = quantization.scales.size() == 1;
+    bool globalScale = quantization.scales.size() <= 1;
     bool isUnitScale = quantization.IsUnitScale();
+    int64_t zp = quantization.zeroPoints.size() ? quantization.zeroPoints.front() : 0;
 
     if ( tensorUsage == TensorUsage::IFM )
     {
@@ -100,7 +101,6 @@ bool EthosU55Constraints::SupportsFusedRescale(OpType opType, TensorUsage tensor
             bool scaleSupported = qs.shift == 0 && static_cast<int16_t>(qs.scale) == qs.scale;
 
             // Make sure the rescale can be done without clipping
-            int64_t zp = quantization.zeroPoints.front();
             int64_t value = (zp < 0 ? int64_t(IntegerMax(rescaleFromType)) : IntegerMin(rescaleFromType));
             value = value - zp;
             value = (value * qs.scale) >> qs.shift;
diff --git a/ethosu/regor/architecture/ethosu85/ethos_u85_constraints.cpp b/ethosu/regor/architecture/ethosu85/ethos_u85_constraints.cpp
index 7988eb91e1b40761cc795f565f5e02de258e97f7..2badd56d0f6ad372c1238fd8384581d0c5529063 100644
--- a/ethosu/regor/architecture/ethosu85/ethos_u85_constraints.cpp
+++ b/ethosu/regor/architecture/ethosu85/ethos_u85_constraints.cpp
@@ -102,8 +102,9 @@ bool EthosU85Constraints::SupportsFusedRescale(OpType opType, TensorUsage tensor
     DataType rescaleToType, DataType opFromType, DataType opToType, const Quantization &quantization)
 {
     auto npuOp = ArchEthosU85::GetHWOp(opType);
-    bool globalScale = quantization.scales.size() == 1;
+    bool globalScale = quantization.scales.size() <= 1;
     bool isUnitScale = quantization.IsUnitScale();
+    int64_t zp = quantization.zeroPoints.size() ? quantization.zeroPoints.front() : 0;
 
     if ( tensorUsage == TensorUsage::IFM )
     {
@@ -118,7 +119,6 @@ bool EthosU85Constraints::SupportsFusedRescale(OpType opType, TensorUsage tensor
             // Make sure shift is valid
             if ( qs.shift < 0 || qs.shift > 63 ) return false;
             // Make sure the rescale can be done without clipping
-            int64_t zp = quantization.zeroPoints.front();
             int64_t value = (zp < 0 ? int64_t(IntegerMax(rescaleFromType)) : IntegerMin(rescaleFromType));
             value = value - zp;
             value = (value * qs.scale) >> qs.shift;
diff --git a/ethosu/regor/compiler/quantization.hpp b/ethosu/regor/compiler/quantization.hpp
index a79212d08f9fb0603c6dee464fe90ebd24645717..dd054078c6b414920316f5a02a7c3b2ddb6f0fee 100644
--- a/ethosu/regor/compiler/quantization.hpp
+++ b/ethosu/regor/compiler/quantization.hpp
@@ -1,5 +1,5 @@
 //
-// SPDX-FileCopyrightText: Copyright 2023-2024 Arm Limited and/or its affiliates <open-source-office@arm.com>
+// SPDX-FileCopyrightText: Copyright 2023-2025 Arm Limited and/or its affiliates <open-source-office@arm.com>
 //
 // SPDX-License-Identifier: Apache-2.0
 //
@@ -57,7 +57,7 @@ public:
     {
         return other.scales == scales && other.zeroPoints == zeroPoints;
     }
-    bool IsUnitScale() const { return Quantization::Unit().scales == scales; }
+    bool IsUnitScale() const { return Quantization::Unit().scales == scales || scales.empty(); }
     explicit operator bool() const { return IsValid(); }
 
     Quantization &operator=(const Quantization &other)