diff --git a/src/main/java/net/fabricmc/loom/extension/ForgeExtensionImpl.java b/src/main/java/net/fabricmc/loom/extension/ForgeExtensionImpl.java
index af190850..953b4782 100644
--- a/src/main/java/net/fabricmc/loom/extension/ForgeExtensionImpl.java
+++ b/src/main/java/net/fabricmc/loom/extension/ForgeExtensionImpl.java
@@ -104,6 +104,10 @@ public class ForgeExtensionImpl implements ForgeExtensionAPI {
 
 	@Override
 	public List<String> getDataGenMods() {
+		if (extension.isNeoForge()) {
+			throw new UnsupportedOperationException("getDataGenMods is not available on NeoForge.");
+		}
+
 		// unmod list prevents uncontrolled additions (we want to create the run config too)
 		return Collections.unmodifiableList(dataGenMods);
 	}
@@ -111,6 +115,10 @@ public class ForgeExtensionImpl implements ForgeExtensionAPI {
 	@SuppressWarnings("Convert2Lambda")
 	@Override
 	public void dataGen(Action<DataGenConsumer> action) {
+		if (extension.isNeoForge()) {
+			throw new UnsupportedOperationException("dataGen is not available on NeoForge.");
+		}
+
 		action.execute(new DataGenConsumer() {
 			@Override
 			public void mod(String... modIds) {