diff --git a/include/WinStd/Win.h b/include/WinStd/Win.h
index dede6b74..eb17eba3 100644
--- a/include/WinStd/Win.h
+++ b/include/WinStd/Win.h
@@ -158,7 +158,7 @@ template<class _Elem, class _Traits, class _Ax> inline VOID GuidToStringW(_In_ L
 /// \param[in ] lpszGuid  String with GUID
 /// \param[out] lpGuid    GUID to store the result to
 ///
-BOOL WINSTD_API StringToGuidA(_In_z_ LPCSTR lpszGuid, _Out_ LPGUID lpGuid);
+BOOL WINSTD_API StringToGuidA(_In_z_ LPCSTR lpszGuid, _Out_ LPGUID lpGuid, _Out_ LPCSTR *lpszGuidEnd = NULL);
 
 ///
 /// Parses string with GUID and stores it to GUID
@@ -166,7 +166,7 @@ BOOL WINSTD_API StringToGuidA(_In_z_ LPCSTR lpszGuid, _Out_ LPGUID lpGuid);
 /// \param[in ] lpszGuid  String with GUID
 /// \param[out] lpGuid    GUID to store the result to
 ///
-BOOL WINSTD_API StringToGuidW(_In_z_ LPCWSTR lpszGuid, _Out_ LPGUID lpGuid);
+BOOL WINSTD_API StringToGuidW(_In_z_ LPCWSTR lpszGuid, _Out_ LPGUID lpGuid, _Out_ LPCWSTR *lpszGuidEnd = NULL);
 
 #ifdef _UNICODE
 #define StringToGuid StringToGuidW
diff --git a/src/Win.cpp b/src/Win.cpp
index 3a051c43..58709a72 100644
--- a/src/Win.cpp
+++ b/src/Win.cpp
@@ -25,7 +25,7 @@
 // StringToGuidA
 //////////////////////////////////////////////////////////////////////
 
-BOOL WINSTD_API StringToGuidA(_In_z_ LPCSTR lpszGuid, _Out_ LPGUID lpGuid)
+BOOL WINSTD_API StringToGuidA(_In_z_ LPCSTR lpszGuid, _Out_ LPGUID lpGuid, _Out_ LPCSTR *lpszGuidEnd)
 {
     GUID g;
     LPSTR lpszEnd;
@@ -80,14 +80,15 @@ BOOL WINSTD_API StringToGuidA(_In_z_ LPCSTR lpszGuid, _Out_ LPGUID lpGuid)
     if (*lpszGuid != '}') return FALSE;
     lpszGuid++;
 
-    if (*lpszGuid != 0) return FALSE;
+    if (lpszGuidEnd)
+        *lpszGuidEnd = lpszGuid;
 
     *lpGuid = g;
     return TRUE;
 }
 
 
-BOOL WINSTD_API StringToGuidW(_In_z_ LPCWSTR lpszGuid, _Out_ LPGUID lpGuid)
+BOOL WINSTD_API StringToGuidW(_In_z_ LPCWSTR lpszGuid, _Out_ LPGUID lpGuid, _Out_ LPCWSTR *lpszGuidEnd)
 {
     GUID g;
     LPWSTR lpszEnd;
@@ -142,7 +143,8 @@ BOOL WINSTD_API StringToGuidW(_In_z_ LPCWSTR lpszGuid, _Out_ LPGUID lpGuid)
     if (*lpszGuid != '}') return FALSE;
     lpszGuid++;
 
-    if (*lpszGuid != 0) return FALSE;
+    if (lpszGuidEnd)
+        *lpszGuidEnd = lpszGuid;
 
     *lpGuid = g;
     return TRUE;