diff --git a/M6502/HarteTest_6502/checker_t.cpp b/M6502/HarteTest_6502/checker_t.cpp
index 495c0ec..562790b 100644
--- a/M6502/HarteTest_6502/checker_t.cpp
+++ b/M6502/HarteTest_6502/checker_t.cpp
@@ -48,7 +48,7 @@ void checker_t::dumpCycle(const cycle_t cycle) {
     dumpCycle(cycle.address(), cycle.value(), cycle.action());
 }
 
-void checker_t::raise(const std::string what, const uint16_t expected, const uint16_t actual) {
+void checker_t::raise(std::string_view what, const uint16_t expected, const uint16_t actual) {
     os()
         << std::setw(2) << std::setfill(' ')
         << what
@@ -58,7 +58,7 @@ void checker_t::raise(const std::string what, const uint16_t expected, const uin
     pushCurrentMessage();
 }
 
-void checker_t::raise(const std::string what, const uint8_t expected, const uint8_t actual) {
+void checker_t::raise(std::string_view what, const uint8_t expected, const uint8_t actual) {
     os()
         << std::setw(2) << std::setfill(' ')
         << what
@@ -70,7 +70,7 @@ void checker_t::raise(const std::string what, const uint8_t expected, const uint
     pushCurrentMessage();
 }
 
-void checker_t::raise(const std::string what, const std::string_view expected, const std::string_view actual) {
+void checker_t::raise(std::string_view what, const std::string_view expected, const std::string_view actual) {
     os()
         << std::setw(0) << std::setfill(' ')
         << what
@@ -79,7 +79,7 @@ void checker_t::raise(const std::string what, const std::string_view expected, c
     pushCurrentMessage();
 }
 
-bool checker_t::check(const std::string what, const uint16_t address, const uint8_t expected, const uint8_t actual) {
+bool checker_t::check(std::string_view what, const uint16_t address, const uint8_t expected, const uint8_t actual) {
     const auto success = actual == expected;
     if (!success) {
         os() << what << ": " << std::setw(4) << std::setfill('0') << (int)address;
diff --git a/M6502/HarteTest_6502/checker_t.h b/M6502/HarteTest_6502/checker_t.h
index d5a8193..9559037 100644
--- a/M6502/HarteTest_6502/checker_t.h
+++ b/M6502/HarteTest_6502/checker_t.h
@@ -42,19 +42,19 @@ private:
 
     void pushCurrentMessage();
 
-    void raise(std::string what, uint16_t expected, uint16_t actual);
-    void raise(std::string what, uint8_t expected, uint8_t actual);
-    void raise(std::string what, std::string_view expected, std::string_view actual);
+    void raise(std::string_view what, uint16_t expected, uint16_t actual);
+    void raise(std::string_view what, uint8_t expected, uint8_t actual);
+    void raise(std::string_view what, std::string_view expected, std::string_view actual);
 
     template<class T>
-    bool check(std::string what, T expected, T actual) {
+    bool check(std::string_view what, T expected, T actual) {
         const auto success = actual == expected;
         if (!success)
             raise(what, expected, actual);
         return success;
     }
 
-    bool check(std::string what, uint16_t address, uint8_t expected, uint8_t actual);
+    bool check(std::string_view what, uint16_t address, uint8_t expected, uint8_t actual);
 
     void addActualCycle(uint16_t address, uint8_t value, std::string action);
     void addActualCycle(EightBit::register16_t address, uint8_t value, std::string action);