diff --git a/impl/getusername.cpp b/impl/getusername.cpp
index b37b1cffc..e911da41b 100644
--- a/impl/getusername.cpp
+++ b/impl/getusername.cpp
@@ -1,7 +1,7 @@
 #include "getusername.h"
 #include <unistd.h>
 
-BOOL GetUserName(WCHAR_T* userName, UINT32* maxLength)
+BOOL GetUserName(WCHAR_T* lpBuffer, LPDWORD lpnSize)
 {
 	return 0;
 }
diff --git a/impl/getusername.h b/impl/getusername.h
index 922a4e96a..7650b94cc 100644
--- a/impl/getusername.h
+++ b/impl/getusername.h
@@ -4,7 +4,7 @@
 
 PAL_BEGIN_EXTERNC
 
-BOOL GetUserName(WCHAR_T* userName, UINT32* maxLength);
+BOOL GetUserName(WCHAR_T* lpBuffer, LPDWORD lpnSize);
 
 PAL_END_EXTERNC