diff --git a/src/net/http/request.go b/src/net/http/request.go
index 54ec1c5593..183606d0ff 100644
--- a/src/net/http/request.go
+++ b/src/net/http/request.go
@@ -175,6 +175,10 @@ type Request struct {
 	// but will return EOF immediately when no body is present.
 	// The Server will close the request body. The ServeHTTP
 	// Handler does not need to.
+	//
+	// Body must allow Read to be called concurrently with Close.
+	// In particular, calling Close should unblock a Read waiting
+	// for input.
 	Body io.ReadCloser
 
 	// GetBody defines an optional func to return a new copy of
diff --git a/src/net/http/server.go b/src/net/http/server.go
index db3a09b993..fab229c92a 100644
--- a/src/net/http/server.go
+++ b/src/net/http/server.go
@@ -890,12 +890,12 @@ func (srv *Server) initialReadLimitSize() int64 {
 type expectContinueReader struct {
 	resp       *response
 	readCloser io.ReadCloser
-	closed     bool
+	closed     atomicBool
 	sawEOF     atomicBool
 }
 
 func (ecr *expectContinueReader) Read(p []byte) (n int, err error) {
-	if ecr.closed {
+	if ecr.closed.isSet() {
 		return 0, ErrBodyReadAfterClose
 	}
 	w := ecr.resp
@@ -917,7 +917,7 @@ func (ecr *expectContinueReader) Read(p []byte) (n int, err error) {
 }
 
 func (ecr *expectContinueReader) Close() error {
-	ecr.closed = true
+	ecr.closed.setTrue()
 	return ecr.readCloser.Close()
 }