diff --git a/dashboard/app/build/handler.go b/dashboard/app/build/handler.go
index b11d584b..258d5c12 100644
--- a/dashboard/app/build/handler.go
+++ b/dashboard/app/build/handler.go
@@ -26,8 +26,11 @@ import (
 	"key"
 )
 
-const commitsPerPage = 30
-const watcherVersion = 3 // must match dashboard/watcher/watcher.go's watcherVersion
+const (
+	commitsPerPage = 30
+	watcherVersion = 3 // must match dashboard/watcher/watcher.go
+	builderVersion = 1 // must match dashboard/builder/http.go
+)
 
 // commitHandler retrieves commit data or records a new commit.
 //
@@ -85,10 +88,9 @@ func commitHandler(r *http.Request) (interface{}, error) {
 		return nil, errors.New("can only POST commits with master key")
 	}
 
-	// For now, the commit watcher doesn't support gccgo,
-	// so only do this check for Go commits.
-	// TODO(adg,cmang): remove this check when gccgo is supported.
-	if dashboardForRequest(r) == goDash {
+	// For now, the commit watcher doesn't support gccgo.
+	// TODO(adg,cmang): remove this exception when gccgo is supported.
+	if dashboardForRequest(r) != gccgoDash {
 		v, _ := strconv.Atoi(r.FormValue("version"))
 		if v != watcherVersion {
 			return nil, fmt.Errorf("rejecting POST from commit watcher; need version %v", watcherVersion)
@@ -524,6 +526,15 @@ func resultHandler(r *http.Request) (interface{}, error) {
 		return nil, errBadMethod(r.Method)
 	}
 
+	// For now, the gccgo builders are using the old stuff.
+	// TODO(adg,cmang): remove this exception when gccgo is updated.
+	if dashboardForRequest(r) != gccgoDash {
+		v, _ := strconv.Atoi(r.FormValue("version"))
+		if v != builderVersion {
+			return nil, fmt.Errorf("rejecting POST from builder; need version %v", builderVersion)
+		}
+	}
+
 	c := contextForRequest(r)
 	res := new(Result)
 	defer r.Body.Close()
diff --git a/dashboard/builder/http.go b/dashboard/builder/http.go
index 3fbad3a8..8d0923c4 100644
--- a/dashboard/builder/http.go
+++ b/dashboard/builder/http.go
@@ -16,6 +16,8 @@ import (
 	"time"
 )
 
+const builderVersion = 1 // keep in sync with dashboard/app/build/handler.go
+
 type obj map[string]interface{}
 
 // dash runs the given method and command on the dashboard.
@@ -24,15 +26,19 @@ type obj map[string]interface{}
 // If resp is non-nil the server's response is decoded into the value pointed
 // to by resp (resp must be a pointer).
 func dash(meth, cmd string, args url.Values, req, resp interface{}) error {
+	argsCopy := url.Values{"version": {fmt.Sprint(builderVersion)}}
+	for k, v := range args {
+		if k == "version" {
+			panic(`dash: reserved args key: "version"`)
+		}
+		argsCopy[k] = v
+	}
 	var r *http.Response
 	var err error
 	if *verbose {
-		log.Println("dash <-", meth, cmd, args, req)
-	}
-	cmd = *dashboard + "/" + cmd
-	if len(args) > 0 {
-		cmd += "?" + args.Encode()
+		log.Println("dash <-", meth, cmd, argsCopy, req)
 	}
+	cmd = *dashboard + "/" + cmd + "?" + argsCopy.Encode()
 	switch meth {
 	case "GET":
 		if req != nil {
diff --git a/dashboard/builder/main.go b/dashboard/builder/main.go
index 35359cb4..211d8af5 100644
--- a/dashboard/builder/main.go
+++ b/dashboard/builder/main.go
@@ -53,7 +53,7 @@ var (
 	buildRevision = flag.String("rev", "", "Build specified revision and exit")
 	buildCmd      = flag.String("cmd", filepath.Join(".", allCmd), "Build command (specify relative to go/src/)")
 	buildTool     = flag.String("tool", "go", "Tool to build.")
-	gcPath        = flag.String("gcpath", "code.google.com/p/go", "Path to download gc from")
+	gcPath        = flag.String("gcpath", "go.googlesource.com/go", "Path to download gc from")
 	gccPath       = flag.String("gccpath", "https://github.com/mirrors/gcc.git", "Path to download gcc from")
 	gccOpts       = flag.String("gccopts", "", "Command-line options to pass to `make` when building gccgo")
 	benchPath     = flag.String("benchpath", "golang.org/x/benchmarks/bench", "Path to download benchmarks from")