diff --git a/src/net/http/fcgi/child.go b/src/net/http/fcgi/child.go
index 756722ba14..dc82bf7c3a 100644
--- a/src/net/http/fcgi/child.go
+++ b/src/net/http/fcgi/child.go
@@ -16,7 +16,6 @@ import (
 	"net/http/cgi"
 	"os"
 	"strings"
-	"sync"
 	"time"
 )
 
@@ -154,7 +153,6 @@ type child struct {
 	conn    *conn
 	handler http.Handler
 
-	mu       sync.Mutex          // protects requests:
 	requests map[uint16]*request // keyed by request ID
 }
 
@@ -193,9 +191,7 @@ var ErrRequestAborted = errors.New("fcgi: request aborted by web server")
 var ErrConnClosed = errors.New("fcgi: connection to web server closed")
 
 func (c *child) handleRecord(rec *record) error {
-	c.mu.Lock()
 	req, ok := c.requests[rec.h.Id]
-	c.mu.Unlock()
 	if !ok && rec.h.Type != typeBeginRequest && rec.h.Type != typeGetValues {
 		// The spec says to ignore unknown request IDs.
 		return nil
@@ -218,9 +214,7 @@ func (c *child) handleRecord(rec *record) error {
 			return nil
 		}
 		req = newRequest(rec.h.Id, br.flags)
-		c.mu.Lock()
 		c.requests[rec.h.Id] = req
-		c.mu.Unlock()
 		return nil
 	case typeParams:
 		// NOTE(eds): Technically a key-value pair can straddle the boundary
@@ -248,8 +242,11 @@ func (c *child) handleRecord(rec *record) error {
 			// TODO(eds): This blocks until the handler reads from the pipe.
 			// If the handler takes a long time, it might be a problem.
 			req.pw.Write(content)
-		} else if req.pw != nil {
-			req.pw.Close()
+		} else {
+			delete(c.requests, req.reqId)
+			if req.pw != nil {
+				req.pw.Close()
+			}
 		}
 		return nil
 	case typeGetValues:
@@ -260,9 +257,7 @@ func (c *child) handleRecord(rec *record) error {
 		// If the filter role is implemented, read the data stream here.
 		return nil
 	case typeAbortRequest:
-		c.mu.Lock()
 		delete(c.requests, rec.h.Id)
-		c.mu.Unlock()
 		c.conn.writeEndRequest(rec.h.Id, 0, statusRequestComplete)
 		if req.pw != nil {
 			req.pw.CloseWithError(ErrRequestAborted)
@@ -309,9 +304,6 @@ func (c *child) serveRequest(req *request, body io.ReadCloser) {
 	// Make sure we serve something even if nothing was written to r
 	r.Write(nil)
 	r.Close()
-	c.mu.Lock()
-	delete(c.requests, req.reqId)
-	c.mu.Unlock()
 	c.conn.writeEndRequest(req.reqId, 0, statusRequestComplete)
 
 	// Consume the entire body, so the host isn't still writing to
@@ -330,8 +322,6 @@ func (c *child) serveRequest(req *request, body io.ReadCloser) {
 }
 
 func (c *child) cleanUp() {
-	c.mu.Lock()
-	defer c.mu.Unlock()
 	for _, req := range c.requests {
 		if req.pw != nil {
 			// race with call to Close in c.serveRequest doesn't matter because
diff --git a/src/net/http/fcgi/fcgi_test.go b/src/net/http/fcgi/fcgi_test.go
index b58111de20..5888783620 100644
--- a/src/net/http/fcgi/fcgi_test.go
+++ b/src/net/http/fcgi/fcgi_test.go
@@ -11,6 +11,7 @@ import (
 	"net/http"
 	"strings"
 	"testing"
+	"time"
 )
 
 var sizeTests = []struct {
@@ -399,3 +400,55 @@ func TestResponseWriterSniffsContentType(t *testing.T) {
 		})
 	}
 }
+
+type signallingNopCloser struct {
+	io.Reader
+	closed chan bool
+}
+
+func (*signallingNopCloser) Write(buf []byte) (int, error) {
+	return len(buf), nil
+}
+
+func (rc *signallingNopCloser) Close() error {
+	close(rc.closed)
+	return nil
+}
+
+// Test whether server properly closes connection when processing slow
+// requests
+func TestSlowRequest(t *testing.T) {
+	pr, pw := io.Pipe()
+	go func(w io.Writer) {
+		for _, buf := range [][]byte{
+			streamBeginTypeStdin,
+			makeRecord(typeStdin, 1, nil),
+		} {
+			pw.Write(buf)
+			time.Sleep(100 * time.Millisecond)
+		}
+	}(pw)
+
+	rc := &signallingNopCloser{pr, make(chan bool)}
+	handlerDone := make(chan bool)
+
+	c := newChild(rc, http.HandlerFunc(func(
+		w http.ResponseWriter,
+		r *http.Request,
+	) {
+		w.WriteHeader(200)
+		close(handlerDone)
+	}))
+	go c.serve()
+	defer c.cleanUp()
+
+	timeout := time.After(2 * time.Second)
+
+	<-handlerDone
+	select {
+	case <-rc.closed:
+		t.Log("FastCGI child closed connection")
+	case <-timeout:
+		t.Error("FastCGI child did not close socket after handling request")
+	}
+}