diff --git a/cmd/godoc/godoc_test.go b/cmd/godoc/godoc_test.go
index 4eec5894ea..b75c07174a 100644
--- a/cmd/godoc/godoc_test.go
+++ b/cmd/godoc/godoc_test.go
@@ -5,7 +5,11 @@
 package main_test
 
 import (
+	"bytes"
+	"fmt"
 	"io/ioutil"
+	"net"
+	"net/http"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -13,6 +17,7 @@ import (
 	"runtime"
 	"strings"
 	"testing"
+	"time"
 )
 
 var godocTests = []struct {
@@ -57,15 +62,18 @@ var godocTests = []struct {
 	},
 }
 
-// Basic regression test for godoc command-line tool.
-func TestGodoc(t *testing.T) {
+// buildGodoc builds the godoc executable.
+// It returns its path, and a cleanup function.
+//
+// TODO(adonovan): opt: do this at most once, and do the cleanup
+// exactly once.  How though?  There's no atexit.
+func buildGodoc(t *testing.T) (bin string, cleanup func()) {
 	tmp, err := ioutil.TempDir("", "godoc-regtest-")
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer os.RemoveAll(tmp)
 
-	bin := filepath.Join(tmp, "godoc")
+	bin = filepath.Join(tmp, "godoc")
 	if runtime.GOOS == "windows" {
 		bin += ".exe"
 	}
@@ -74,6 +82,13 @@ func TestGodoc(t *testing.T) {
 		t.Fatalf("Building godoc: %v", err)
 	}
 
+	return bin, func() { os.RemoveAll(tmp) }
+}
+
+// Basic regression test for godoc command-line tool.
+func TestCLI(t *testing.T) {
+	bin, cleanup := buildGodoc(t)
+	defer cleanup()
 	for _, test := range godocTests {
 		cmd := exec.Command(bin, test.args...)
 		cmd.Args[0] = "godoc"
@@ -96,3 +111,68 @@ func TestGodoc(t *testing.T) {
 		}
 	}
 }
+
+func serverAddress(t *testing.T) string {
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		ln, err = net.Listen("tcp6", "[::1]:0")
+	}
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer ln.Close()
+	return ln.Addr().String()
+}
+
+func waitForServer(t *testing.T, address string) {
+	// Poll every 50ms for a total of 5s.
+	for i := 0; i < 100; i++ {
+		time.Sleep(50 * time.Millisecond)
+		conn, err := net.Dial("tcp", address)
+		if err != nil {
+			continue
+		}
+		conn.Close()
+		return
+	}
+	t.Fatalf("Server %q failed to respond in 5 seconds", address)
+}
+
+// Basic integration test for godoc HTTP interface.
+func TestWeb(t *testing.T) {
+	bin, cleanup := buildGodoc(t)
+	defer cleanup()
+	addr := serverAddress(t)
+	cmd := exec.Command(bin, fmt.Sprintf("-http=%s", addr))
+	cmd.Stdout = os.Stderr
+	cmd.Stderr = os.Stderr
+	cmd.Args[0] = "godoc"
+	if err := cmd.Start(); err != nil {
+		t.Fatalf("failed to start godoc: %s", err)
+	}
+	defer cmd.Process.Kill()
+	waitForServer(t, addr)
+	tests := []struct{ path, substr string }{
+		{"/", "Go is an open source programming language"},
+		{"/pkg/fmt/", "Package fmt implements formatted I/O"},
+		{"/src/pkg/fmt/", "scan_test.go"},
+		{"/src/pkg/fmt/print.go", "// Println formats using"},
+	}
+	for _, test := range tests {
+		url := fmt.Sprintf("http://%s%s", addr, test.path)
+		resp, err := http.Get(url)
+		if err != nil {
+			t.Errorf("GET %s failed: %s", url, err)
+			continue
+		}
+		body, err := ioutil.ReadAll(resp.Body)
+		resp.Body.Close()
+		if err != nil {
+			t.Errorf("GET %s: failed to read body: %s (response: %v)", url, err, resp)
+		}
+		if bytes.Index(body, []byte(test.substr)) < 0 {
+			t.Errorf("GET %s: want substring %q in body, got:\n%s",
+				url, test.substr, string(body))
+		}
+	}
+}
diff --git a/godoc/analysis/analysis.go b/godoc/analysis/analysis.go
index 3cadd89af0..32a8d357a1 100644
--- a/godoc/analysis/analysis.go
+++ b/godoc/analysis/analysis.go
@@ -218,6 +218,9 @@ func (res *Result) fileInfo(url string) *fileInfo {
 	res.mu.Lock()
 	fi, ok := res.fileInfos[url]
 	if !ok {
+		if res.fileInfos == nil {
+			res.fileInfos = make(map[string]*fileInfo)
+		}
 		fi = new(fileInfo)
 		res.fileInfos[url] = fi
 	}
@@ -240,6 +243,9 @@ func (res *Result) pkgInfo(importPath string) *pkgInfo {
 	res.mu.Lock()
 	pi, ok := res.pkgInfos[importPath]
 	if !ok {
+		if res.pkgInfos == nil {
+			res.pkgInfos = make(map[string]*pkgInfo)
+		}
 		pi = new(pkgInfo)
 		res.pkgInfos[importPath] = pi
 	}
@@ -297,9 +303,6 @@ func (a *analysis) posURL(pos token.Pos, len int) string {
 // enabled by the pta flag.
 //
 func Run(pta bool, result *Result) {
-	result.fileInfos = make(map[string]*fileInfo)
-	result.pkgInfos = make(map[string]*pkgInfo)
-
 	conf := loader.Config{
 		SourceImports:   true,
 		AllowTypeErrors: true,