diff --git a/ui/build/config.go b/ui/build/config.go
index 7370627..cd6d549 100644
--- a/ui/build/config.go
+++ b/ui/build/config.go
@@ -345,12 +345,7 @@
 		return
 	}
 
-	b := &smpb.BuildConfig{
-		ForceUseGoma: proto.Bool(config.ForceUseGoma()),
-		UseGoma:      proto.Bool(config.UseGoma()),
-		UseRbe:       proto.Bool(config.UseRBE()),
-	}
-	ctx.Metrics.BuildConfig(b)
+	ctx.Metrics.BuildConfig(buildConfig(config))
 
 	s := &smpb.SystemResourceInfo{
 		TotalPhysicalMemory: proto.Uint64(config.TotalRAM()),
@@ -359,6 +354,16 @@
 	ctx.Metrics.SystemResourceInfo(s)
 }
 
+func buildConfig(config Config) *smpb.BuildConfig {
+	return &smpb.BuildConfig{
+		ForceUseGoma:    proto.Bool(config.ForceUseGoma()),
+		UseGoma:         proto.Bool(config.UseGoma()),
+		UseRbe:          proto.Bool(config.UseRBE()),
+		BazelAsNinja:    proto.Bool(config.UseBazel()),
+		BazelMixedBuild: proto.Bool(config.bazelBuildMode() == mixedBuild),
+	}
+}
+
 // getConfigArgs processes the command arguments based on the build action and creates a set of new
 // arguments to be accepted by Config.
 func getConfigArgs(action BuildAction, dir string, ctx Context, args []string) []string {