diff --git a/libs/binder/Android.bp b/libs/binder/Android.bp
index bf3699c..ae0fb01 100644
--- a/libs/binder/Android.bp
+++ b/libs/binder/Android.bp
@@ -258,7 +258,9 @@
         "-DBINDER_DISABLE_NATIVE_HANDLE",
         "-DBINDER_DISABLE_BLOB",
         "-DBINDER_NO_LIBBASE",
+        // TODO: switch to "vendor: true" rather than copying this
         // Trusty libbinder uses vendor stability for its binders
+        "-D__ANDROID_VENDOR__",
         "-D__ANDROID_VNDK__",
         "-U__ANDROID__",
         "-D__TRUSTY__",
diff --git a/libs/binder/Stability.cpp b/libs/binder/Stability.cpp
index c432b3a..665dfea 100644
--- a/libs/binder/Stability.cpp
+++ b/libs/binder/Stability.cpp
@@ -73,6 +73,14 @@
     (void)setRepr(binder, getLocalLevel(), REPR_NONE);
 }
 
+// after deprecation of the VNDK, these should be aliases. At some point
+// all references to __ANDROID_VNDK__ should be replaced by __ANDROID_VENDOR__
+// but for right now, check that this condition holds because some
+// places check __ANDROID_VNDK__ and some places check __ANDROID_VENDOR__
+#if defined(__ANDROID_VNDK__) != defined(__ANDROID_VENDOR__)
+#error "__ANDROID_VNDK__ and __ANDROID_VENDOR__ should be aliases"
+#endif
+
 Stability::Level Stability::getLocalLevel() {
 #ifdef __ANDROID_APEX__
 #error "APEX can't use libbinder (must use libbinder_ndk)"
diff --git a/libs/binder/trusty/kernel/rules.mk b/libs/binder/trusty/kernel/rules.mk
index 788184d..5cbe0af 100644
--- a/libs/binder/trusty/kernel/rules.mk
+++ b/libs/binder/trusty/kernel/rules.mk
@@ -69,6 +69,7 @@
 	-DBINDER_DISABLE_NATIVE_HANDLE \
 	-DBINDER_DISABLE_BLOB \
 	-DBINDER_NO_LIBBASE \
+	-D__ANDROID_VENDOR__ \
 	-D__ANDROID_VNDK__ \
 
 MODULE_DEPS += \
diff --git a/libs/binder/trusty/rules.mk b/libs/binder/trusty/rules.mk
index e0f821f..f2f140d 100644
--- a/libs/binder/trusty/rules.mk
+++ b/libs/binder/trusty/rules.mk
@@ -72,6 +72,7 @@
 	-DBINDER_DISABLE_NATIVE_HANDLE \
 	-DBINDER_DISABLE_BLOB \
 	-DBINDER_NO_LIBBASE \
+	-D__ANDROID_VENDOR__ \
 	-D__ANDROID_VNDK__ \
 
 # libbinder has some deprecated declarations that we want to produce warnings