diff --git a/dlls/shlwapi/string.c b/dlls/shlwapi/string.c
index 4d77c3f2e99..8c4cb711ea5 100644
--- a/dlls/shlwapi/string.c
+++ b/dlls/shlwapi/string.c
@@ -1509,7 +1509,7 @@ HRESULT WINAPI StrRetToBufA (LPSTRRET src, const ITEMIDLIST *pidl, LPSTR dest, U
 
 	  default:
 	    FIXME("unknown type!\n");
-	    return FALSE;
+	    return E_NOTIMPL;
 	}
 	return S_OK;
 }
@@ -1559,7 +1559,7 @@ HRESULT WINAPI StrRetToBufW (LPSTRRET src, const ITEMIDLIST *pidl, LPWSTR dest,
 
 	  default:
 	    FIXME("unknown type!\n");
-	    return FALSE;
+	    return E_NOTIMPL;
 	}
 	return S_OK;
 }