diff --git a/developer/src/kmcmplib/src/kmx_u16.cpp b/common/cpp/km_u16.cpp
similarity index 97%
rename from developer/src/kmcmplib/src/kmx_u16.cpp
rename to common/cpp/km_u16.cpp
index 708c82dc04e..84a6c4a75e7 100644
--- a/developer/src/kmcmplib/src/kmx_u16.cpp
+++ b/common/cpp/km_u16.cpp
@@ -1,16 +1,12 @@
+/*
+ * Keyman is copyright (C) SIL International. MIT License.
+ *
+ * std::u16string functions and string conversion utility functions
+ */
 
-//#include "../../kmcompx/include/kmcompx.h"
-#include <kmcompx.h>
-#include "kmx_u16.h"
-
-#include <xstring.h>
-#include <km_types.h>
-#include <kmx_file.h>
-#include <codecvt>
-#include <locale>
 #include <stdarg.h>
-#include <algorithm>
 #include "utfcodec.hpp"
+#include "km_u16.h"
 
 /**   string <- wstring
  * @brief  Obtain a std::string from a std::wstring
diff --git a/developer/src/kmcmplib/src/kmx_u16.h b/common/include/km_u16.h
similarity index 97%
rename from developer/src/kmcmplib/src/kmx_u16.h
rename to common/include/km_u16.h
index 4ebcdb601dd..f0c2c2d16c1 100644
--- a/developer/src/kmcmplib/src/kmx_u16.h
+++ b/common/include/km_u16.h
@@ -1,11 +1,8 @@
 #pragma once
 
-#include <cmath>
-#include <vector>
-#include <ctype.h>
 #include <string>
 #include <cstring>
-#include "kmcompx.h"
+#include <km_types.h>
 
 /** @brief Obtain a std::string from a std::wstring */
 std::string string_from_wstring(std::wstring const wstr);
diff --git a/developer/src/kmcmplib/include/kmcompx.h b/developer/src/kmcmplib/include/kmcompx.h
index 7e7b2704961..9d7ca75508b 100644
--- a/developer/src/kmcmplib/include/kmcompx.h
+++ b/developer/src/kmcmplib/include/kmcompx.h
@@ -3,11 +3,6 @@
 
 // TODO: merge with kmcmplib.h
 
-typedef wchar_t     KMX_WCHART;
-typedef KMX_DWORD * PKMX_DWORD;
-typedef char *      PKMX_STR;
-typedef KMX_WCHAR*  PKMX_WCHAR ;
-
 // TODO: these defines are copied out of unicode.h, because unicode.h still
 //       has windows-specific types. These should be remerged at a future date
 
diff --git a/developer/src/kmcmplib/src/CasedKeys.cpp b/developer/src/kmcmplib/src/CasedKeys.cpp
index 0a0508f11a4..0883c401ce3 100644
--- a/developer/src/kmcmplib/src/CasedKeys.cpp
+++ b/developer/src/kmcmplib/src/CasedKeys.cpp
@@ -1,13 +1,14 @@
 
 #include "pch.h"
 
+#include "km_u16.h"
+#include "../../../../common/windows/cpp/include/vkeys.h"
+
 #include "compfile.h"
 #include "kmn_compiler_errors.h"
-#include "../../../../common/windows/cpp/include/vkeys.h"
 #include "kmcmplib.h"
 
 #include "CharToKeyConversion.h"
-#include "kmx_u16.h"
 #include "xstring.h"
 
 namespace kmcmp {
diff --git a/developer/src/kmcmplib/src/CheckForDuplicates.cpp b/developer/src/kmcmplib/src/CheckForDuplicates.cpp
index 9e5d63b9ef8..e0fa0094bcb 100644
--- a/developer/src/kmcmplib/src/CheckForDuplicates.cpp
+++ b/developer/src/kmcmplib/src/CheckForDuplicates.cpp
@@ -1,11 +1,11 @@
 
 #include "pch.h"
 
+#include <km_u16.h>
 #include "compfile.h"
 #include <kmn_compiler_errors.h>
 #include "kmcmplib.h"
 #include <xstring.h>
-#include "kmx_u16.h"
 #include <kmcompx.h>
 
 #include "CheckForDuplicates.h"
diff --git a/developer/src/kmcmplib/src/Compiler.cpp b/developer/src/kmcmplib/src/Compiler.cpp
index 03f39823667..3893a728559 100644
--- a/developer/src/kmcmplib/src/Compiler.cpp
+++ b/developer/src/kmcmplib/src/Compiler.cpp
@@ -102,7 +102,7 @@
 
 #include "UnreachableRules.h"
 #include "CheckForDuplicates.h"
-#include "kmx_u16.h"
+#include "km_u16.h"
 
 /* These macros are adapted from winnt.h and legacy use only */
 #define MAKELANGID(p, s)       ((((uint16_t)(s)) << 10) | (uint16_t)(p))
diff --git a/developer/src/kmcmplib/src/meson.build b/developer/src/kmcmplib/src/meson.build
index 260df09b838..51acf704090 100644
--- a/developer/src/kmcmplib/src/meson.build
+++ b/developer/src/kmcmplib/src/meson.build
@@ -78,13 +78,13 @@ lib = library('kmcmplib',
   'cp1252.cpp',
   'DeprecationChecks.cpp',
   'Edition.cpp',
-  'kmx_u16.cpp',
   'NamedCodeConstants.cpp',
   'UnreachableRules.cpp',
   'uset-api.cpp',
   'versioning.cpp',
   'virtualcharkeys.cpp',
   'xstring.cpp',
+  '../../../../common/cpp/km_u16.cpp',
   '../../../../common/cpp/utfcodec.cpp',
   '../../../../common/windows/cpp/src/ConvertUTF.c',
   '../../../../common/windows/cpp/src/crc32.cpp',
diff --git a/developer/src/kmcmplib/src/pch.h b/developer/src/kmcmplib/src/pch.h
index 358e28998ab..80bb639fb8b 100644
--- a/developer/src/kmcmplib/src/pch.h
+++ b/developer/src/kmcmplib/src/pch.h
@@ -4,7 +4,7 @@
 
 #define USE_CHAR16_T
 #include <kmx_file.h>
-#include "kmx_u16.h"
+#include <km_u16.h>
 #include <kmcompx.h>
 
 #include "../../../../common/windows/cpp/include/crc32.h"
diff --git a/developer/src/kmcmplib/tests/gtest-compiler-test.cpp b/developer/src/kmcmplib/tests/gtest-compiler-test.cpp
index 22b38dccc67..1c205976452 100644
--- a/developer/src/kmcmplib/tests/gtest-compiler-test.cpp
+++ b/developer/src/kmcmplib/tests/gtest-compiler-test.cpp
@@ -1,7 +1,7 @@
 #include <gtest/gtest.h>
+#include <km_u16.h>
 #include "../include/kmcompx.h"
 #include "../include/kmcmplibapi.h"
-#include "../src/kmx_u16.h"
 #include "../src/compfile.h"
 #include "../src/CompilerErrors.h"
 #include "../../common/include/kmn_compiler_errors.h"
diff --git a/developer/src/kmcmplib/tests/gtest-kmx_u16-test.cpp b/developer/src/kmcmplib/tests/gtest-km_u16-test.cpp
similarity index 94%
rename from developer/src/kmcmplib/tests/gtest-kmx_u16-test.cpp
rename to developer/src/kmcmplib/tests/gtest-km_u16-test.cpp
index aa1dca1de08..b67957bd317 100644
--- a/developer/src/kmcmplib/tests/gtest-kmx_u16-test.cpp
+++ b/developer/src/kmcmplib/tests/gtest-km_u16-test.cpp
@@ -1,9 +1,9 @@
 #include <gtest/gtest.h>
-#include "../src/kmx_u16.h"
+#include <km_u16.h>
+#include <km_types.h>
 #include "../src/compfile.h"
-#include "../../../../common/include/km_types.h"
 
-TEST(kmx_u16_Test, u16chr) {
+TEST(km_u16_Test, u16chr) {
   KMX_WCHAR str[LINESIZE];
 
   u16cpy(str, u"abc");
@@ -14,7 +14,7 @@ TEST(kmx_u16_Test, u16chr) {
   EXPECT_EQ(3, u16chr(str, '\0') - str); // locate null terminator
 }
 
-TEST(kmx_u16_Test, u16chr_compare_to_strchr) {
+TEST(km_u16_Test, u16chr_compare_to_strchr) {
   // Compare behaviour of strchr:
   char str[LINESIZE];
 
@@ -26,7 +26,7 @@ TEST(kmx_u16_Test, u16chr_compare_to_strchr) {
   EXPECT_EQ(3, strchr(str, '\0') - str); // locate null terminator
 }
 
-TEST(kmx_u16_Test, u16tok_char_delim) {
+TEST(km_u16_Test, u16tok_char_delim) {
   // For char delimiter: KMX_WCHAR * u16tok(KMX_WCHAR *p, const KMX_WCHAR ch,  KMX_WCHAR **ctx) ;
 
 	KMX_WCHAR str[LINESIZE];
@@ -67,7 +67,7 @@ TEST(kmx_u16_Test, u16tok_char_delim) {
 	EXPECT_TRUE(!u16cmp(u"def", ctx));
 }
 
-TEST(kmx_u16_Test, u16tok_str_delim) {
+TEST(km_u16_Test, u16tok_str_delim) {
   // For string delimiter: KMX_WCHAR * u16tok(KMX_WCHAR* p, const KMX_WCHAR* ch, KMX_WCHAR** ctx) ;
 
 	KMX_WCHAR str[LINESIZE];
@@ -126,7 +126,7 @@ TEST(kmx_u16_Test, u16tok_str_delim) {
   EXPECT_EQ(nullptr, ctx);
 }
 
-TEST(kmx_u16_Test, u16tok_str_compare_to_strtok) {
+TEST(km_u16_Test, u16tok_str_compare_to_strtok) {
   // Compare behaviour of strtok:
 	char str[LINESIZE];
 
diff --git a/developer/src/kmcmplib/tests/meson.build b/developer/src/kmcmplib/tests/meson.build
index a5b6476c889..65915d1e9d9 100644
--- a/developer/src/kmcmplib/tests/meson.build
+++ b/developer/src/kmcmplib/tests/meson.build
@@ -168,7 +168,7 @@ gtestcompilertest = executable('gtest-compiler-test', 'gtest-compiler-test.cpp',
 
 test('gtest-compiler-test', gtestcompilertest)
 
-gtestkmx_u16test = executable('gtest-kmx_u16-test', 'gtest-kmx_u16-test.cpp',
+gtest_km_u16_test = executable('gtest-km_u16-test', 'gtest-km_u16-test.cpp',
     cpp_args: defns + flags,
     include_directories: inc,
     name_suffix: name_suffix,
@@ -177,4 +177,4 @@ gtestkmx_u16test = executable('gtest-kmx_u16-test', 'gtest-kmx_u16-test.cpp',
     dependencies: [ icuuc_dep, gtest_dep, gmock_dep ],
   )
 
-test('gtest-kmx_u16-test', gtestkmx_u16test)
+test('gtest-km_u16-test', gtest_km_u16_test)
diff --git a/developer/src/kmcmplib/tests/util_filesystem.cpp b/developer/src/kmcmplib/tests/util_filesystem.cpp
index 4ca210cff93..0873ff13288 100644
--- a/developer/src/kmcmplib/tests/util_filesystem.cpp
+++ b/developer/src/kmcmplib/tests/util_filesystem.cpp
@@ -117,19 +117,6 @@ FILE* Open_File(const KMX_CHAR* Filename, const KMX_CHAR* mode) {
 #endif
 };
 
-FILE* Open_File(const KMX_WCHART* Filename, const KMX_WCHART* mode) {
-#ifdef _MSC_VER
-  std::wstring cpath = Filename; //, cmode = mode;
-  std::replace(cpath.begin(), cpath.end(), '/', '\\');
-  return _wfsopen(cpath.c_str(), mode, _SH_DENYWR);
-#else
-  std::string cpath, cmode;
-  cpath = string_from_wstring(Filename);
-  cmode = string_from_wstring(mode);
-  return fopen_wrapper(cpath.c_str(), cmode.c_str());
-#endif
-};
-
 FILE* Open_File(const KMX_WCHAR* Filename, const KMX_WCHAR* mode) {
 #ifdef _MSC_VER
   std::wstring cpath = wstring_from_u16string(Filename);
diff --git a/developer/src/kmcmplib/tests/util_filesystem.h b/developer/src/kmcmplib/tests/util_filesystem.h
index 4c94dae6bf4..c35967b05e8 100644
--- a/developer/src/kmcmplib/tests/util_filesystem.h
+++ b/developer/src/kmcmplib/tests/util_filesystem.h
@@ -1,12 +1,11 @@
 #pragma once
 
 #include <stdio.h>
-#include "../src/kmx_u16.h"
+#include <km_u16.h>
 
 // Opens files on windows and non-windows platforms. Datatypes for Filename and mode must be the same.
 // returns FILE* if file could be opened; FILE needs to be closed in calling function
 FILE* Open_File(const KMX_CHAR* Filename, const KMX_CHAR* mode);
-FILE* Open_File(const KMX_WCHART* Filename, const KMX_WCHART* mode);
 FILE* Open_File(const KMX_WCHAR* Filename, const KMX_WCHAR* mode);
 KMX_BOOL kmcmp_FileExists(const KMX_CHAR *filename);
 KMX_BOOL kmcmp_FileExists(const KMX_WCHAR *filename);