diff --git a/ui/build/build.go b/ui/build/build.go
index 9d5c330e1..54a4c27e5 100644
--- a/ui/build/build.go
+++ b/ui/build/build.go
@@ -283,11 +283,16 @@ func Build(ctx Context, config Config) {
 	}
 
 	rbeCh := make(chan bool)
+	var rbePanic any
 	if config.StartRBE() {
 		cleanupRBELogsDir(ctx, config)
+		checkRBERequirements(ctx, config)
 		go func() {
+			defer func() {
+				rbePanic = recover()
+				close(rbeCh)
+			}()
 			startRBE(ctx, config)
-			close(rbeCh)
 		}()
 		defer DumpRBEMetrics(ctx, config, filepath.Join(config.LogsDir(), "rbe_metrics.pb"))
 	} else {
@@ -345,6 +350,11 @@ func Build(ctx Context, config Config) {
 	}
 
 	<-rbeCh
+	if rbePanic != nil {
+		// If there was a ctx.Fatal in startRBE, rethrow it.
+		panic(rbePanic)
+	}
+
 	if what&RunNinja != 0 {
 		if what&RunKati != 0 {
 			installCleanIfNecessary(ctx, config)
diff --git a/ui/build/rbe.go b/ui/build/rbe.go
index 19a54dfc2..fa04207e0 100644
--- a/ui/build/rbe.go
+++ b/ui/build/rbe.go
@@ -95,14 +95,10 @@ func cleanupRBELogsDir(ctx Context, config Config) {
 	}
 }
 
-func startRBE(ctx Context, config Config) {
+func checkRBERequirements(ctx Context, config Config) {
 	if !config.GoogleProdCredsExist() && prodCredsAuthType(config) {
 		ctx.Fatalf("Unable to start RBE reproxy\nFAILED: Missing LOAS credentials.")
 	}
-	ctx.BeginTrace(metrics.RunSetupTool, "rbe_bootstrap")
-	defer ctx.EndTrace()
-
-	ctx.Status.Status("Starting rbe...")
 
 	if u := ulimitOrFatal(ctx, config, "-u"); u < rbeLeastNProcs {
 		ctx.Fatalf("max user processes is insufficient: %d; want >= %d.\n", u, rbeLeastNProcs)
@@ -115,6 +111,13 @@ func startRBE(ctx Context, config Config) {
 			ctx.Fatalf("Unable to create logs dir (%v) for RBE: %v", config.rbeProxyLogsDir, err)
 		}
 	}
+}
+
+func startRBE(ctx Context, config Config) {
+	ctx.BeginTrace(metrics.RunSetupTool, "rbe_bootstrap")
+	defer ctx.EndTrace()
+
+	ctx.Status.Status("Starting rbe...")
 
 	cmd := Command(ctx, config, "startRBE bootstrap", rbeCommand(ctx, config, bootstrapCmd))