diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 33253b1..5caaa7e 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -9,7 +9,7 @@ Android Studio.
 
 Fortunately, there's not many dependencies:
 - OpenJDK 8
-- Android SDK: build tools `30.0.3`, platform `30`
+- Android SDK: build tools (minimum `28.0.1`), platform `30`
 - Make sure to have the `$ANDROID_HOME` environment variable set.
 
 For Nix users, there's a `shell.nix` for setting-up the right environment.
diff --git a/Makefile b/Makefile
index 10f7fb4..7a8f7f8 100644
--- a/Makefile
+++ b/Makefile
@@ -105,4 +105,4 @@ _build/classes.dex: $(JAVA_FILES) $(R_FILE)
 		-classpath $(ANDROID_PLATFORM)/android.jar:$(EXTRA_JARS) \
 		-sourcepath $(SRC_DIR):$(GEN_DIR) \
 		$^
-	$(ANDROID_BUILD_TOOLS)/dx --dex --output="$@" $(OBJ_DIR) $(subst :, ,$(EXTRA_JARS))
+	$(ANDROID_BUILD_TOOLS)/d8 --output $(@D) $(OBJ_DIR)/*/*/* $(subst :, ,$(EXTRA_JARS))