diff --git a/include/internal/catch_common.hpp b/include/internal/catch_common.hpp
index 2342ae61..7ad5b1ca 100644
--- a/include/internal/catch_common.hpp
+++ b/include/internal/catch_common.hpp
@@ -21,8 +21,11 @@ namespace Catch {
     bool contains( std::string const& s, std::string const& infix ) {
         return s.find( infix ) != std::string::npos;
     }
+    char toLowerCh(char c) {
+        return static_cast<char>( ::tolower( c ) );
+    }
     void toLowerInPlace( std::string& s ) {
-        std::transform( s.begin(), s.end(), s.begin(), ::tolower );
+        std::transform( s.begin(), s.end(), s.begin(), toLowerCh );
     }
     std::string toLower( std::string const& s ) {
         std::string lc = s;
diff --git a/include/internal/catch_test_case_registry_impl.hpp b/include/internal/catch_test_case_registry_impl.hpp
index 04bd37fc..a70b019b 100644
--- a/include/internal/catch_test_case_registry_impl.hpp
+++ b/include/internal/catch_test_case_registry_impl.hpp
@@ -24,9 +24,9 @@
 #endif
 
 namespace Catch {
-    
+
     struct RandomNumberGenerator {
-        typedef int result_type;
+        typedef std::ptrdiff_t result_type;
 
         result_type operator()( result_type n ) const { return std::rand() % n; }