diff --git a/.changeset/require-multirewarddistributor-evm-config.md b/.changeset/require-multirewarddistributor-evm-config.md
new file mode 100644
index 0000000..3fa371d
--- /dev/null
+++ b/.changeset/require-multirewarddistributor-evm-config.md
@@ -0,0 +1,5 @@
+---
+"@moonwell-fi/moonwell-sdk": minor
+---
+
+Require `multiRewardDistributor` at the type level for EVM comptroller environments. **Type-breaking** for direct callers of `createContractsConfig`: a config with a `comptroller` and no `governor` that omits `multiRewardDistributor` no longer compiles. `createContractsConfig` now rejects a contracts config that defines a `comptroller` but no `governor` (i.e. Base/Optimism/Ethereum) unless it also defines `multiRewardDistributor` — closing the gap that let Ethereum ship without it and silently break reward claims (MOO-413). Moonbeam and Moonriver, which use the on-chain `governor` + WELL precompile reward model, are unaffected and correctly continue to omit it. A runtime invariant test across `publicEnvironments` backstops the type guard.
diff --git a/src/environments/contracts-invariants.test.ts b/src/environments/contracts-invariants.test.ts
new file mode 100644
index 0000000..045b23f
--- /dev/null
+++ b/src/environments/contracts-invariants.test.ts
@@ -0,0 +1,49 @@
+import { describe, expect, test } from "vitest";
+import { publicEnvironments } from "./index.js";
+
+// Runtime companion to the `createContractsConfig` compile-time guard in
+// types/config.ts. Every EVM comptroller environment — one that has a
+// `comptroller` but no Moonbeam-style on-chain `governor` — must wire a
+// `multiRewardDistributor`. Without it the app's reward-claim flow falls back
+// to the Moonbeam `0x…0808` precompile `batchAll` path, which reverts on these
+// chains (the MOO-413 regression, which shipped on Ethereum). The input type
+// enforces this at the `createContractsConfig` call site; this test is the
+// universal net — it iterates the wired `publicEnvironments`, so it also covers
+// any environment built outside that factory and catches an `as`-cast that
+// bypasses the type. Moonbeam/Moonriver use the `governor` + WELL precompile
+// reward model and correctly have no MRD, so the `governor` discriminator
+// excludes them.
+describe("contract config invariants across public environments", () => {
+  type ContractRef = { address?: string } | undefined;
+  const envs = Object.entries(publicEnvironments) as Array<
+    [
+      string,
+      {
+        contracts?: {
+          comptroller?: ContractRef;
+          governor?: ContractRef;
+          multiRewardDistributor?: ContractRef;
+        };
+      },
+    ]
+  >;
+
+  const evmComptrollerEnvs = envs.filter(
+    ([, env]) => !!env.contracts?.comptroller && !env.contracts?.governor,
+  );
+
+  test("Base, Optimism, and Ethereum are detected as EVM comptroller chains", () => {
+    expect(evmComptrollerEnvs.map(([key]) => key)).toEqual(
+      expect.arrayContaining(["base", "optimism", "ethereum"]),
+    );
+  });
+
+  test("every EVM comptroller environment defines multiRewardDistributor", () => {
+    for (const [key, env] of evmComptrollerEnvs) {
+      expect(
+        env.contracts?.multiRewardDistributor?.address,
+        `${key} is an EVM comptroller chain and must define multiRewardDistributor`,
+      ).toMatch(/^0x[0-9a-fA-F]{40}$/);
+    }
+  });
+});
diff --git a/src/environments/types/config.ts b/src/environments/types/config.ts
index b7d3a11..fce7683 100644
--- a/src/environments/types/config.ts
+++ b/src/environments/types/config.ts
@@ -236,9 +236,27 @@ export const createMorphoMarketConfig = <const tokens, const markets>(config: {
   markets: MorphoMarketsConfig<markets, tokens>;
 }) => config.markets as Prettify<markets>;
 
+// Moonwell's EVM comptroller chains (Base, Optimism, Ethereum) distribute WELL
+// rewards through a MultiRewardDistributor, so omitting `multiRewardDistributor`
+// silently breaks reward claims — the app's claim flow then falls back to the
+// Moonbeam `0x…0808` precompile path, which reverts on these chains. That gap
+// shipped once already (MOO-413: Ethereum had no MRD). The Moonbeam-family home
+// chains (Moonbeam, Moonriver) instead use the on-chain `governor` + WELL
+// precompile reward model and legitimately have no MRD. Encode the distinction:
+// a config with a `comptroller` but no `governor` is an EVM comptroller chain
+// and must define `multiRewardDistributor`, so dropping it fails to compile.
+type RequireMultiRewardDistributor<contracts> = contracts extends {
+  comptroller: Address;
+}
+  ? contracts extends { governor: Address }
+    ? unknown
+    : { multiRewardDistributor: Address }
+  : unknown;
+
 export const createContractsConfig = <const tokens, const contracts>(config: {
   tokens: TokensConfig<tokens>;
-  contracts: ContractsConfig<contracts, tokens>;
+  contracts: ContractsConfig<contracts, tokens> &
+    RequireMultiRewardDistributor<contracts>;
 }) => {
   return config.contracts as Prettify<contracts>;
 };
diff --git a/test/vitest.config.ts b/test/vitest.config.ts
index 084b1de..e0dd847 100644
--- a/test/vitest.config.ts
+++ b/test/vitest.config.ts
@@ -54,6 +54,7 @@ export default defineConfig({
       "src/client/createMoonwellClient.test.ts",
       "src/common/getBlockNumberAtTimestamp.test.ts",
       "src/environments/definitions/ethereum/environment.test.ts",
+      "src/environments/contracts-invariants.test.ts",
     ],
     setupFiles: [join(__dirname, "./setup.ts")],
     hookTimeout: 60_000,