diff --git a/tests/testapk/src/native/testbinary.cpp b/tests/testapk/src/native/testbinary.cpp
index 682ab2a..9bd594b 100644
--- a/tests/testapk/src/native/testbinary.cpp
+++ b/tests/testapk/src/native/testbinary.cpp
@@ -24,6 +24,8 @@
 using aidl::android::system::keystore2::IKeystoreSecurityLevel;
 using aidl::android::system::keystore2::IKeystoreService;
 
+extern void testlib_sub();
+
 namespace {
 
 bool test_keystore() {
@@ -52,6 +54,7 @@
             printf(" ");
         }
     }
+    testlib_sub();
     printf("\n");
 
     __system_property_set("debug.microdroid.app.run", "true");
diff --git a/tests/testapk/src/native/testlib.cpp b/tests/testapk/src/native/testlib.cpp
new file mode 100644
index 0000000..792c6c8
--- /dev/null
+++ b/tests/testapk/src/native/testlib.cpp
@@ -0,0 +1,5 @@
+#include <sys/system_properties.h>
+
+void testlib_sub() {
+    __system_property_set("debug.microdroid.app.sublib.run", "true");
+}