diff --git a/include/internal/catch_approx.hpp b/include/internal/catch_approx.hpp
index 4370ab3e..f5dba61a 100644
--- a/include/internal/catch_approx.hpp
+++ b/include/internal/catch_approx.hpp
@@ -8,7 +8,7 @@
 #ifndef TWOBLUECUBES_CATCH_APPROX_HPP_INCLUDED
 #define TWOBLUECUBES_CATCH_APPROX_HPP_INCLUDED
 
-#include "catch_tostring.hpp"
+#include "catch_tostring.h"
 
 #include <cmath>
 #include <limits>
diff --git a/include/internal/catch_capture.hpp b/include/internal/catch_capture.hpp
index 4dda29db..1578f996 100644
--- a/include/internal/catch_capture.hpp
+++ b/include/internal/catch_capture.hpp
@@ -15,7 +15,7 @@
 #include "catch_debugger.h"
 #include "catch_context.h"
 #include "catch_common.h"
-#include "catch_tostring.hpp"
+#include "catch_tostring.h"
 #include "catch_interfaces_registry_hub.h"
 #include "catch_interfaces_config.h"
 #include "internal/catch_compiler_capabilities.h"
diff --git a/include/internal/catch_exception_translator_registry.hpp b/include/internal/catch_exception_translator_registry.hpp
index 50e4b6e0..ffa14b17 100644
--- a/include/internal/catch_exception_translator_registry.hpp
+++ b/include/internal/catch_exception_translator_registry.hpp
@@ -9,7 +9,7 @@
 #define TWOBLUECUBES_CATCH_EXCEPTION_TRANSLATOR_REGISTRY_HPP_INCLUDED
 
 #include "catch_interfaces_exception.h"
-#include "catch_tostring.hpp"
+#include "catch_tostring.h"
 
 #ifdef __OBJC__
 #import "Foundation/Foundation.h"
diff --git a/include/internal/catch_expression_lhs.hpp b/include/internal/catch_expression_lhs.hpp
index 81753fbc..e3436ede 100644
--- a/include/internal/catch_expression_lhs.hpp
+++ b/include/internal/catch_expression_lhs.hpp
@@ -10,7 +10,7 @@
 
 #include "catch_expressionresult_builder.h"
 #include "catch_evaluate.hpp"
-#include "catch_tostring.hpp"
+#include "catch_tostring.h"
 
 namespace Catch {
 
diff --git a/include/internal/catch_expressionresult_builder.h b/include/internal/catch_expressionresult_builder.h
index 96beb4ac..8d4ec145 100644
--- a/include/internal/catch_expressionresult_builder.h
+++ b/include/internal/catch_expressionresult_builder.h
@@ -8,7 +8,7 @@
 #ifndef TWOBLUECUBES_CATCH_ASSERTIONRESULT_BUILDER_H_INCLUDED
 #define TWOBLUECUBES_CATCH_ASSERTIONRESULT_BUILDER_H_INCLUDED
 
-#include "catch_tostring.hpp"
+#include "catch_tostring.h"
 #include "catch_assertionresult.h"
 #include "catch_result_type.h"
 #include "catch_evaluate.hpp"
diff --git a/include/internal/catch_tostring.hpp b/include/internal/catch_tostring.h
similarity index 99%
rename from include/internal/catch_tostring.hpp
rename to include/internal/catch_tostring.h
index 85bfa740..95717463 100644
--- a/include/internal/catch_tostring.hpp
+++ b/include/internal/catch_tostring.h
@@ -180,6 +180,8 @@ std::string toString( T const& value ) {
 
 // Built in overloads
 
+///////// !TBD: move this into impl file
+
 inline std::string toString( std::string const& value ) {
     std::string s = value;
     if( getCurrentContext().getConfig()->showInvisibles() ) {
diff --git a/include/reporters/catch_reporter_junit.hpp b/include/reporters/catch_reporter_junit.hpp
index 57395930..63f7e148 100644
--- a/include/reporters/catch_reporter_junit.hpp
+++ b/include/reporters/catch_reporter_junit.hpp
@@ -10,7 +10,7 @@
 
 #include "catch_reporter_bases.hpp"
 
-#include "../internal/catch_tostring.hpp"
+#include "../internal/catch_tostring.h"
 #include "../internal/catch_reporter_registrars.hpp"
 #include "../internal/catch_xmlwriter.hpp"
 
diff --git a/projects/XCode/CatchSelfTest/CatchSelfTest.xcodeproj/project.pbxproj b/projects/XCode/CatchSelfTest/CatchSelfTest.xcodeproj/project.pbxproj
index e4a77c0d..f4c8dde3 100644
--- a/projects/XCode/CatchSelfTest/CatchSelfTest.xcodeproj/project.pbxproj
+++ b/projects/XCode/CatchSelfTest/CatchSelfTest.xcodeproj/project.pbxproj
@@ -80,6 +80,7 @@
 		26948284179A9AB900ED166E /* SectionTrackerTests.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = SectionTrackerTests.cpp; path = ../../../SelfTest/SectionTrackerTests.cpp; sourceTree = "<group>"; };
 		26948287179EF7F900ED166E /* catch_test_case_tracker.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = catch_test_case_tracker.hpp; sourceTree = "<group>"; };
 		2694A1FB16A0000E004816E3 /* catch_text.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = catch_text.cpp; sourceTree = "<group>"; };
+		269831E519078C1600BB0CE0 /* catch_tostring.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = catch_tostring.h; sourceTree = "<group>"; };
 		26AEAF1617BEA18E009E32C9 /* catch_platform.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = catch_platform.h; sourceTree = "<group>"; };
 		26DACF2F17206D3400A21326 /* catch_text.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = catch_text.h; sourceTree = "<group>"; };
 		4A084F1C15DACEEA0027E631 /* catch_test_case_info.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = catch_test_case_info.hpp; sourceTree = "<group>"; };
@@ -152,7 +153,6 @@
 		4A90B59B15D0F61A00EF71BC /* catch_interfaces_generators.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = catch_interfaces_generators.h; sourceTree = "<group>"; };
 		4A90B59D15D24FE900EF71BC /* catch_assertionresult.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; lineEnding = 0; path = catch_assertionresult.hpp; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.cpp; };
 		4A90B59E15D2521E00EF71BC /* catch_expressionresult_builder.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; lineEnding = 0; path = catch_expressionresult_builder.hpp; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.cpp; };
-		4A9D84B11558FC0400FBB209 /* catch_tostring.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; lineEnding = 0; path = catch_tostring.hpp; sourceTree = "<group>"; };
 		4A9D84B315599AC900FBB209 /* catch_expressionresult_builder.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; lineEnding = 0; path = catch_expressionresult_builder.h; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.objcpp; };
 		4AA7B8B4165428BA003155F6 /* catch_version.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; name = catch_version.hpp; path = ../../../../include/internal/catch_version.hpp; sourceTree = "<group>"; };
 		4AB1C73514F97BDA00F31DF7 /* catch_console_colour_impl.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; lineEnding = 0; path = catch_console_colour_impl.hpp; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.cpp; };
@@ -344,6 +344,7 @@
 		4AC91CBD155C37B500DC5117 /* Assertions */ = {
 			isa = PBXGroup;
 			children = (
+				269831E519078C1600BB0CE0 /* catch_tostring.h */,
 				4A6D0C4D149B3E3D00DB3EAA /* catch_evaluate.hpp */,
 				4A6D0C4F149B3E3D00DB3EAA /* catch_generators.hpp */,
 				4A6D0C5C149B3E3D00DB3EAA /* catch_result_type.h */,
@@ -351,7 +352,6 @@
 				4A9D84B315599AC900FBB209 /* catch_expressionresult_builder.h */,
 				261488FE184DC32F0041FBEB /* catch_section.h */,
 				4A3D7DD01503869D005F9203 /* catch_matchers.hpp */,
-				4A9D84B11558FC0400FBB209 /* catch_tostring.hpp */,
 				4A6D0C46149B3E3D00DB3EAA /* catch_approx.hpp */,
 				4A6D0C47149B3E3D00DB3EAA /* catch_capture.hpp */,
 				4AC91CCE155CF02800DC5117 /* catch_expression_lhs.hpp */,