diff --git a/tests/expression/1.0/Android.mk b/tests/expression/1.0/Android.mk
index 21bc08e..804af71 100644
--- a/tests/expression/1.0/Android.mk
+++ b/tests/expression/1.0/Android.mk
@@ -17,9 +17,9 @@
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/IExpression.hal
 $(GEN): PRIVATE_OUTPUT_DIR := $(intermediates)
 $(GEN): PRIVATE_CUSTOM_TOOL = \
-    $(PRIVATE_HIDL) -o $(PRIVATE_OUTPUT_DIR) \
-    -Lc++ -randroid.hardware:hardware/interfaces \
-    android.hardware.tests.expression@1.0::IExpression
+        $(PRIVATE_HIDL) -o $(PRIVATE_OUTPUT_DIR) \
+        -Lc++ -randroid.hardware:hardware/interfaces \
+        android.hardware.tests.expression@1.0::IExpression
 
 $(GEN): $(LOCAL_PATH)/IExpression.hal
 	$(transform-generated-source)
@@ -36,9 +36,9 @@
 $(GEN): $(LOCAL_PATH)/IExpression.hal
 $(GEN): PRIVATE_OUTPUT_DIR := $(intermediates)
 $(GEN): PRIVATE_CUSTOM_TOOL = \
-    $(PRIVATE_HIDL) -o $(PRIVATE_OUTPUT_DIR) \
-    -Lc++ -randroid.hardware:hardware/interfaces \
-    android.hardware.tests.expression@1.0::IExpressionExt
+        $(PRIVATE_HIDL) -o $(PRIVATE_OUTPUT_DIR) \
+        -Lc++ -randroid.hardware:hardware/interfaces \
+        android.hardware.tests.expression@1.0::IExpressionExt
 
 $(GEN): $(LOCAL_PATH)/IExpressionExt.hal
 	$(transform-generated-source)
@@ -46,10 +46,10 @@
 
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(intermediates)
 LOCAL_SHARED_LIBRARIES := \
-  libhidl \
-  libhwbinder \
-  libutils \
-  libcutils \
+    libhidl \
+    libhwbinder \
+    libutils \
+    libcutils \
 
 LOCAL_MULTILIB := both
 include $(BUILD_SHARED_LIBRARY)
@@ -73,9 +73,9 @@
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/IExpression.hal
 $(GEN): PRIVATE_OUTPUT_DIR := $(intermediates)
 $(GEN): PRIVATE_CUSTOM_TOOL = \
-    $(PRIVATE_HIDL) -o $(PRIVATE_OUTPUT_DIR) \
-    -Ljava -randroid.hardware:hardware/interfaces \
-    android.hardware.tests.expression@1.0::IExpression
+        $(PRIVATE_HIDL) -o $(PRIVATE_OUTPUT_DIR) \
+        -Ljava -randroid.hardware:hardware/interfaces \
+        android.hardware.tests.expression@1.0::IExpression
 
 $(GEN): $(LOCAL_PATH)/IExpression.hal
 	$(transform-generated-source)
@@ -92,9 +92,9 @@
 $(GEN): $(LOCAL_PATH)/IExpression.hal
 $(GEN): PRIVATE_OUTPUT_DIR := $(intermediates)
 $(GEN): PRIVATE_CUSTOM_TOOL = \
-    $(PRIVATE_HIDL) -o $(PRIVATE_OUTPUT_DIR) \
-    -Ljava -randroid.hardware:hardware/interfaces \
-    android.hardware.tests.expression@1.0::IExpressionExt
+        $(PRIVATE_HIDL) -o $(PRIVATE_OUTPUT_DIR) \
+        -Ljava -randroid.hardware:hardware/interfaces \
+        android.hardware.tests.expression@1.0::IExpressionExt
 
 $(GEN): $(LOCAL_PATH)/IExpressionExt.hal
 	$(transform-generated-source)
@@ -121,13 +121,32 @@
 $(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/IExpression.hal
 $(GEN): PRIVATE_OUTPUT_DIR := $(intermediates)
 $(GEN): PRIVATE_CUSTOM_TOOL = \
-    $(PRIVATE_HIDL) -o $(PRIVATE_OUTPUT_DIR) \
-    -Ljava -randroid.hardware:hardware/interfaces \
-    android.hardware.tests.expression@1.0::IExpression
+        $(PRIVATE_HIDL) -o $(PRIVATE_OUTPUT_DIR) \
+        -Ljava -randroid.hardware:hardware/interfaces \
+        android.hardware.tests.expression@1.0::IExpression
 
 $(GEN): $(LOCAL_PATH)/IExpression.hal
 	$(transform-generated-source)
 LOCAL_GENERATED_SOURCES += $(GEN)
+
+#
+# Build IExpressionExt.hal
+#
+GEN := $(intermediates)/android/hardware/tests/expression/1.0/IExpressionExt.java
+$(GEN): $(HIDL)
+$(GEN): PRIVATE_HIDL := $(HIDL)
+$(GEN): PRIVATE_DEPS := $(LOCAL_PATH)/IExpressionExt.hal
+$(GEN): PRIVATE_DEPS += $(LOCAL_PATH)/IExpression.hal
+$(GEN): $(LOCAL_PATH)/IExpression.hal
+$(GEN): PRIVATE_OUTPUT_DIR := $(intermediates)
+$(GEN): PRIVATE_CUSTOM_TOOL = \
+        $(PRIVATE_HIDL) -o $(PRIVATE_OUTPUT_DIR) \
+        -Ljava -randroid.hardware:hardware/interfaces \
+        android.hardware.tests.expression@1.0::IExpressionExt
+
+$(GEN): $(LOCAL_PATH)/IExpressionExt.hal
+	$(transform-generated-source)
+LOCAL_GENERATED_SOURCES += $(GEN)
 include $(BUILD_STATIC_JAVA_LIBRARY)