diff --git a/src/win32/utf-conv.c b/src/win32/utf-conv.c
index 76f1e4237..0a705c0ad 100644
--- a/src/win32/utf-conv.c
+++ b/src/win32/utf-conv.c
@@ -32,19 +32,16 @@ void gitwin_set_utf8(void)
 wchar_t* gitwin_to_utf16(const char* str)
 {
 	wchar_t* ret;
-	size_t cb;
+	int cb;
 
 	if (!str)
 		return NULL;
 
-	cb = strlen(str) * sizeof(wchar_t);
+	cb = MultiByteToWideChar(_active_codepage, 0, str, -1, NULL, 0);
 	if (cb == 0)
 		return (wchar_t *)git__calloc(1, sizeof(wchar_t));
 
-	/* Add space for null terminator */
-	cb += sizeof(wchar_t);
-
-	ret = (wchar_t *)git__malloc(cb);
+	ret = (wchar_t *)git__malloc(cb * sizeof(wchar_t));
 	if (!ret)
 		return NULL;
 
@@ -59,7 +56,8 @@ wchar_t* gitwin_to_utf16(const char* str)
 
 int gitwin_append_utf16(wchar_t *buffer, const char *str, size_t len)
 {
-	int result = MultiByteToWideChar(_active_codepage, 0, str, -1, buffer, (int)len);
+	int result = MultiByteToWideChar(
+		_active_codepage, 0, str, -1, buffer, (int)len);
 	if (result == 0)
 		giterr_set(GITERR_OS, "Could not convert string to UTF-16");
 	return result;
@@ -68,23 +66,22 @@ int gitwin_append_utf16(wchar_t *buffer, const char *str, size_t len)
 char* gitwin_from_utf16(const wchar_t* str)
 {
 	char* ret;
-	size_t cb;
+	int cb;
 
 	if (!str)
 		return NULL;
 
-	cb = wcslen(str) * sizeof(char);
+	cb = WideCharToMultiByte(_active_codepage, 0, str, -1, NULL, 0, NULL, NULL);
 	if (cb == 0)
 		return (char *)git__calloc(1, sizeof(char));
 
-	/* Add space for null terminator */
-	cb += sizeof(char);
-
 	ret = (char*)git__malloc(cb);
 	if (!ret)
 		return NULL;
 
-	if (WideCharToMultiByte(_active_codepage, 0, str, -1, ret, (int)cb, NULL, NULL) == 0) {
+	if (WideCharToMultiByte(
+		_active_codepage, 0, str, -1, ret, (int)cb, NULL, NULL) == 0)
+	{
 		giterr_set(GITERR_OS, "Could not convert string to UTF-8");
 		git__free(ret);
 		ret = NULL;
diff --git a/tests-clar/core/env.c b/tests-clar/core/env.c
index bd1a94244..abe7bf87c 100644
--- a/tests-clar/core/env.c
+++ b/tests-clar/core/env.c
@@ -15,12 +15,16 @@ static char *cl_getenv(const char *name)
 
 	cl_assert(name_utf16);
 	alloc_len = GetEnvironmentVariableW(name_utf16, NULL, 0);
-	if (alloc_len < 0)
+	if (alloc_len <= 0)
 		return NULL;
+
 	cl_assert(value_utf16 = git__calloc(alloc_len, sizeof(wchar_t)));
+
 	value_len = GetEnvironmentVariableW(name_utf16, value_utf16, alloc_len);
 	cl_assert_equal_i(value_len, alloc_len - 1);
+
 	cl_assert(value_utf8 = gitwin_from_utf16(value_utf16));
+
 	git__free(value_utf16);
 
 	return value_utf8;