diff --git a/src/dev/hsa/hsa_device.hh b/src/dev/hsa/hsa_device.hh
index 157c459e59..5b6f388d4e 100644
--- a/src/dev/hsa/hsa_device.hh
+++ b/src/dev/hsa/hsa_device.hh
@@ -101,7 +101,8 @@ class HSADevice : public DmaDevice
         fatal("%s does not need HSA driver\n", name());
     }
     virtual void
-    updateHsaSignal(Addr signal_handle, uint64_t signal_value)
+    updateHsaSignal(Addr signal_handle, uint64_t signal_value,
+        HsaSignalCallbackFunction function = [] (const uint64_t &) { })
     {
         fatal("%s does not have HSA signal update functionality.\n", name());
     }
diff --git a/src/gpu-compute/gpu_command_processor.hh b/src/gpu-compute/gpu_command_processor.hh
index c78ae0bdd5..67cda7d169 100644
--- a/src/gpu-compute/gpu_command_processor.hh
+++ b/src/gpu-compute/gpu_command_processor.hh
@@ -90,7 +90,7 @@ class GPUCommandProcessor : public HSADevice
 
     void updateHsaSignal(Addr signal_handle, uint64_t signal_value,
                          HsaSignalCallbackFunction function =
-                            [] (const uint64_t &) { });
+                            [] (const uint64_t &) { }) override;
 
     uint64_t functionalReadHsaSignal(Addr signal_handle) override;