diff --git a/ui/build/soong.go b/ui/build/soong.go
index b20237c..bb5cbf0 100644
--- a/ui/build/soong.go
+++ b/ui/build/soong.go
@@ -133,6 +133,13 @@
 			"-j", strconv.Itoa(config.Parallel()),
 			"--frontend_file", fifo,
 			"-f", filepath.Join(config.SoongOutDir(), file))
+
+		// For Bazel mixed builds.
+		cmd.Environment.Set("BAZEL_PATH", "./tools/bazel")
+		cmd.Environment.Set("BAZEL_HOME", filepath.Join(config.BazelOutDir(), "bazelhome"))
+		cmd.Environment.Set("BAZEL_OUTPUT_BASE", filepath.Join(config.BazelOutDir(), "output"))
+		cmd.Environment.Set("BAZEL_WORKSPACE", absPath(ctx, "."))
+
 		cmd.Environment.Set("SOONG_SANDBOX_SOONG_BUILD", "true")
 		cmd.Sandbox = soongSandbox
 		cmd.RunAndStreamOrFatal()