diff --git a/impl/getusername.cpp b/impl/getusername.cpp
index e2bd4e837..ba6f64ad8 100644
--- a/impl/getusername.cpp
+++ b/impl/getusername.cpp
@@ -10,7 +10,7 @@
 #include <unicode/uchar.h>
 
 /*
-  GetUserName function
+  GetUserNameW function
 
   https://msdn.microsoft.com/en-us/library/windows/desktop/ms724432(v=vs.85).aspx
 
@@ -63,7 +63,7 @@
   If the function fails, the return value is zero. To get extended
   error information, call GetLastError.
 */
-BOOL GetUserName(WCHAR_T *lpBuffer, LPDWORD lpnSize)
+BOOL GetUserNameW(WCHAR_T *lpBuffer, LPDWORD lpnSize)
 {
 	const std::string utf8 = "UTF-8";
 
diff --git a/impl/getusername.h b/impl/getusername.h
index 50c6b1d5c..ad6099c4b 100644
--- a/impl/getusername.h
+++ b/impl/getusername.h
@@ -6,6 +6,6 @@ PAL_BEGIN_EXTERNC
 
 // WCHAR_T * is a Unicode LPTSTR
 // See https://msdn.microsoft.com/en-us/library/windows/desktop/aa383751(v=vs.85).aspx#LPTSTR
-BOOL GetUserName(WCHAR_T *lpBuffer, LPDWORD lpnSize);
+BOOL GetUserNameW(WCHAR_T *lpBuffer, LPDWORD lpnSize);
 
 PAL_END_EXTERNC
diff --git a/tests/test-getusername.cpp b/tests/test-getusername.cpp
index 1aab90721..5a6a8535c 100644
--- a/tests/test-getusername.cpp
+++ b/tests/test-getusername.cpp
@@ -24,7 +24,7 @@ protected:
 		lpnSize = size;
 		// allocate a WCHAR_T buffer to receive username
 		lpBuffer.assign(lpnSize, '\0');
-		result = GetUserName(&lpBuffer[0], &lpnSize);
+		result = GetUserNameW(&lpBuffer[0], &lpnSize);
 	}
 
 	void TestSuccess() {
@@ -79,7 +79,7 @@ protected:
 
 TEST_F(GetUserNameTest, BufferAsNullButNotBufferSize) {
 	lpnSize = 1;
-	result = GetUserName(NULL, &lpnSize);
+	result = GetUserNameW(NULL, &lpnSize);
 
 	TestInvalidParameter();
 	// does not reset lpnSize
@@ -88,7 +88,7 @@ TEST_F(GetUserNameTest, BufferAsNullButNotBufferSize) {
 
 TEST_F(GetUserNameTest, BufferSizeAsNullButNotBuffer) {
 	lpBuffer.push_back('\0');
-	result = GetUserName(&lpBuffer[0], NULL);
+	result = GetUserNameW(&lpBuffer[0], NULL);
 
 	TestInvalidParameter();
 }