diff --git a/src/middleware/isFromOwner.ts b/src/middleware/isFromOwner.ts
index a40ca1d..7d29624 100644
--- a/src/middleware/isFromOwner.ts
+++ b/src/middleware/isFromOwner.ts
@@ -9,7 +9,10 @@ export const isFromOwner: AgentMiddleware = async (ctx, next) => {
 
   const senderAddress = await ctx.getSenderAddress();
 
-  if (senderAddress === ownerAddress) {
+  // Ethereum addresses are case-insensitive, and the owner address may be
+  // provided in a different casing (e.g. EIP-55 checksummed) than the sender
+  // address returned by the SDK, so compare them case-insensitively.
+  if (senderAddress?.toLowerCase() === ownerAddress.toLowerCase()) {
     // Continue message processing
     await next();
   } else {