diff --git a/src/Client.ts b/src/Client.ts
index 217d9e5de..50b233abf 100644
--- a/src/Client.ts
+++ b/src/Client.ts
@@ -779,7 +779,7 @@ async function getUserContactFromNetwork(
       address = undefined
     }
 
-    if (address === peerAddress) {
+    if (address?.toLowerCase() === peerAddress.toLowerCase()) {
       return keyBundle
     }
   }
@@ -815,7 +815,7 @@ async function getUserContactsFromNetwork(
         try {
           const keyBundle = decodeContactBundle(env.message)
           const signingAddress = await keyBundle?.walletSignatureAddress()
-          if (address === signingAddress) {
+          if (address.toLowerCase() === signingAddress.toLowerCase()) {
             return keyBundle
           } else {
             console.info('Received contact bundle with incorrect address')
diff --git a/src/conversations/Conversations.ts b/src/conversations/Conversations.ts
index 1423daf35..efabd1e86 100644
--- a/src/conversations/Conversations.ts
+++ b/src/conversations/Conversations.ts
@@ -360,7 +360,8 @@ export default class Conversations<ContentTypes = any> {
       if (msg instanceof DecodedMessage && msg.contentTopic === introTopic) {
         const convo = new ConversationV1(
           this.client,
-          msg.recipientAddress === this.client.address
+          msg.recipientAddress?.toLowerCase() ===
+          this.client.address.toLowerCase()
             ? (msg.senderAddress as string)
             : (msg.recipientAddress as string),
           msg.sent
@@ -474,7 +475,7 @@ export default class Conversations<ContentTypes = any> {
       throw new Error(`Recipient ${peerAddress} is not on the XMTP network`)
     }
 
-    if (peerAddress === this.client.address) {
+    if (peerAddress.toLowerCase() === this.client.address.toLowerCase()) {
       throw new Error('self messaging not supported')
     }
 
@@ -487,7 +488,7 @@ export default class Conversations<ContentTypes = any> {
     if (!context?.conversationId) {
       const v1Convos = await this.listV1Conversations()
       const matchingConvo = v1Convos.find(
-        (convo) => convo.peerAddress === peerAddress
+        (convo) => convo.peerAddress.toLowerCase() === peerAddress.toLowerCase()
       )
       // If intro already exists, return V1 conversation
       // if both peers have V1 compatible key bundles
@@ -516,7 +517,7 @@ export default class Conversations<ContentTypes = any> {
 
     // Define a function for matching V2 conversations
     const matcherFn = (convo: Conversation<ContentTypes>) =>
-      convo.peerAddress === peerAddress &&
+      convo.peerAddress.toLowerCase() === peerAddress.toLowerCase() &&
       isMatchingContext(context, convo.context ?? undefined)
 
     const existing = await this.getV2ConversationsFromKeystore()
@@ -571,7 +572,8 @@ export default class Conversations<ContentTypes = any> {
 
   private getPeerAddress(message: MessageV1): string {
     const peerAddress =
-      message.recipientAddress === this.client.address
+      message.recipientAddress?.toLowerCase() ===
+      this.client.address.toLowerCase()
         ? message.senderAddress
         : message.recipientAddress
 
diff --git a/test/conversations/Conversation.test.ts b/test/conversations/Conversation.test.ts
index 4bab7bf10..e7e354768 100644
--- a/test/conversations/Conversation.test.ts
+++ b/test/conversations/Conversation.test.ts
@@ -128,6 +128,9 @@ describe('conversation', () => {
       expect(
         alice.conversations.newConversation(alice.address)
       ).rejects.toThrow('self messaging not supported')
+      expect(
+        alice.conversations.newConversation(alice.address.toLowerCase())
+      ).rejects.toThrow('self messaging not supported')
     })
 
     it('can send a prepared message v1', async () => {
diff --git a/test/conversations/Conversations.test.ts b/test/conversations/Conversations.test.ts
index aff73b602..77aca19ff 100644
--- a/test/conversations/Conversations.test.ts
+++ b/test/conversations/Conversations.test.ts
@@ -261,6 +261,19 @@ describe('conversations', () => {
       expect(bobConvo instanceof ConversationV1).toBeTruthy()
     })
 
+    it('does not create a duplicate conversation with an address case mismatch', async () => {
+      const convo1 = await alice.conversations.newConversation(bob.address)
+      await convo1.send('gm')
+      const convos = await alice.conversations.list()
+      expect(convos).toHaveLength(1)
+      const convo2 = await alice.conversations.newConversation(
+        bob.address.toLowerCase()
+      )
+      await convo2.send('gm')
+      const convos2 = await alice.conversations.list()
+      expect(convos2).toHaveLength(1)
+    })
+
     it('continues to use v1 conversation even after upgrading bundle', async () => {
       const aliceConvo = await alice.conversations.newConversation(bob.address)
       await aliceConvo.send('gm')