diff --git a/singleflight/singleflight.go b/singleflight/singleflight.go
index ff2c2ee4..e6e467ea 100644
--- a/singleflight/singleflight.go
+++ b/singleflight/singleflight.go
@@ -53,12 +53,15 @@ func (g *Group) Do(key string, fn func() (interface{}, error)) (interface{}, err
 	g.m[key] = c
 	g.mu.Unlock()
 
-	c.val, c.err = fn()
-	c.wg.Done()
+	afterFn := func() {
+		c.wg.Done()
+		g.mu.Lock()
+		delete(g.m, key)
+		g.mu.Unlock()
+	}
+	defer afterFn()
 
-	g.mu.Lock()
-	delete(g.m, key)
-	g.mu.Unlock()
+	c.val, c.err = fn()
 
 	return c.val, c.err
 }