diff --git a/gee-cache/day3-http-server/geecache/http.go b/gee-cache/day3-http-server/geecache/http.go
index b9b994e..5437610 100644
--- a/gee-cache/day3-http-server/geecache/http.go
+++ b/gee-cache/day3-http-server/geecache/http.go
@@ -58,5 +58,8 @@ func (p *HTTPPool) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	w.Header().Set("Content-Type", "application/octet-stream")
-	w.Write(view.ByteSlice())
+	_, err = w.Write(view.ByteSlice())
+	if err != nil {
+		return
+	}
 }
diff --git a/gee-web/day2-context/gee/context.go b/gee-web/day2-context/gee/context.go
index 72a7fe7..c2537fb 100644
--- a/gee-web/day2-context/gee/context.go
+++ b/gee-web/day2-context/gee/context.go
@@ -56,8 +56,9 @@ func (c *Context) JSON(code int, obj interface{}) {
 	c.Status(code)
 	encoder := json.NewEncoder(c.Writer)
 	if err := encoder.Encode(obj); err != nil {
-		http.Error(c.Writer, err.Error(), 500)
+		panic(err)
 	}
+	return
 }
 
 func (c *Context) Data(code int, data []byte) {
diff --git a/gee-web/day5-middleware/gee/context.go b/gee-web/day5-middleware/gee/context.go
index 1885e0c..5fb87b5 100644
--- a/gee-web/day5-middleware/gee/context.go
+++ b/gee-web/day5-middleware/gee/context.go
@@ -42,8 +42,10 @@ func (c *Context) Next() {
 }
 
 func (c *Context) Fail(code int, err string) {
-	c.index = len(c.handlers)
-	c.JSON(code, H{"message": err})
+	if c == nil {
+		c.index = len(c.handlers)
+		c.JSON(code, H{"message": err})
+	}
 }
 
 func (c *Context) Param(key string) string {