diff --git a/include/internal/catch_test_case_registry_impl.hpp b/include/internal/catch_test_case_registry_impl.hpp
index fda70aae..5fc2b727 100644
--- a/include/internal/catch_test_case_registry_impl.hpp
+++ b/include/internal/catch_test_case_registry_impl.hpp
@@ -22,7 +22,7 @@
 namespace Catch {
 
     struct LexSort {
-        bool operator() (TestCase i,TestCase j) const { return (i<j);}
+        bool operator() (const TestCase& i, const TestCase& j) const { return (i<j);}
     };
     struct RandomNumberGenerator {
         int operator()( int n ) const { return std::rand() % n; }
diff --git a/single_include/catch.hpp b/single_include/catch.hpp
index faaef35e..95c1390c 100644
--- a/single_include/catch.hpp
+++ b/single_include/catch.hpp
@@ -5926,7 +5926,7 @@ namespace Catch {
 namespace Catch {
 
     struct LexSort {
-        bool operator() (TestCase i,TestCase j) const { return (i<j);}
+        bool operator() (const TestCase& i, const TestCase& j) const { return (i<j);}
     };
     struct RandomNumberGenerator {
         int operator()( int n ) const { return std::rand() % n; }