diff --git a/source/nsswitch/winbindd_user.c b/source/nsswitch/winbindd_user.c
index 6f5a86f43ae..249b9ccd8eb 100644
--- a/source/nsswitch/winbindd_user.c
+++ b/source/nsswitch/winbindd_user.c
@@ -58,6 +58,8 @@ static BOOL winbindd_fill_pwent(char *dom_name, char *user_name,
 		return False;
 	}
 
+	strlower_m(user_name);
+
 	/* Username */
 
 	fill_domain_username(output_username, dom_name, user_name); 
diff --git a/source/nsswitch/winbindd_util.c b/source/nsswitch/winbindd_util.c
index a9197d35616..66006905385 100644
--- a/source/nsswitch/winbindd_util.c
+++ b/source/nsswitch/winbindd_util.c
@@ -648,6 +648,7 @@ void fill_domain_username(fstring name, const char *domain, const char *user)
 			 domain, lp_winbind_separator(),
 			 user);
 	}
+	strlower_m(name);
 }
 
 /*