diff --git a/library/src/androidTest/java/org/xmtp/android/library/ReactionTest.kt b/library/src/androidTest/java/org/xmtp/android/library/ReactionTest.kt
index 2ec03df49..ee7ae3fe5 100644
--- a/library/src/androidTest/java/org/xmtp/android/library/ReactionTest.kt
+++ b/library/src/androidTest/java/org/xmtp/android/library/ReactionTest.kt
@@ -1,10 +1,12 @@
 package org.xmtp.android.library
 
 import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.google.protobuf.kotlin.toByteStringUtf8
 import org.junit.Assert.assertEquals
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.xmtp.android.library.codecs.ContentTypeReaction
+import org.xmtp.android.library.codecs.EncodedContent
 import org.xmtp.android.library.codecs.Reaction
 import org.xmtp.android.library.codecs.ReactionAction
 import org.xmtp.android.library.codecs.ReactionCodec
@@ -14,6 +16,50 @@ import org.xmtp.android.library.messages.walletAddress
 @RunWith(AndroidJUnit4::class)
 class ReactionTest {
 
+    @Test
+    fun testCanDecodeLegacyForm() {
+        val codec = ReactionCodec()
+
+        // This is how clients send reactions now.
+        val canonicalEncoded = EncodedContent.newBuilder().also {
+            it.type = ContentTypeReaction
+            it.content = """
+                {
+                    "action": "added",
+                    "content": "smile",
+                    "reference": "abc123",
+                    "schema": "shortcode"
+                }
+            """.trimIndent().toByteStringUtf8()
+        }.build()
+
+        // Previously, some clients sent reactions like this.
+        // So we test here to make sure we can still decode them.
+        val legacyEncoded = EncodedContent.newBuilder().also {
+            it.type = ContentTypeReaction
+            it.putAllParameters(
+                mapOf(
+                    "action" to "added",
+                    "reference" to "abc123",
+                    "schema" to "shortcode",
+                )
+            )
+            it.content = "smile".toByteStringUtf8()
+        }.build()
+
+        val canonical = codec.decode(canonicalEncoded)
+        val legacy = codec.decode(legacyEncoded)
+
+        assertEquals(ReactionAction.added, canonical.action)
+        assertEquals(ReactionAction.added, legacy.action)
+        assertEquals("smile", canonical.content)
+        assertEquals("smile", legacy.content)
+        assertEquals("abc123", canonical.reference)
+        assertEquals("abc123", legacy.reference)
+        assertEquals(ReactionSchema.shortcode, canonical.schema)
+        assertEquals(ReactionSchema.shortcode, legacy.schema)
+    }
+
     @Test
     fun testCanUseReactionCodec() {
         Client.register(codec = ReactionCodec())
diff --git a/library/src/main/java/org/xmtp/android/library/codecs/ReactionCodec.kt b/library/src/main/java/org/xmtp/android/library/codecs/ReactionCodec.kt
index 3eebe1aef..824b52265 100644
--- a/library/src/main/java/org/xmtp/android/library/codecs/ReactionCodec.kt
+++ b/library/src/main/java/org/xmtp/android/library/codecs/ReactionCodec.kt
@@ -37,7 +37,20 @@ data class ReactionCodec(override var contentType: ContentTypeId = ContentTypeRe
     }
 
     override fun decode(content: EncodedContent): Reaction {
-        val gson = GsonBuilder().create()
-        return gson.fromJson(content.content.toStringUtf8(), Reaction::class.java)
+        val text = content.content.toStringUtf8()
+
+        // First try to decode it in the canonical form.
+        try {
+            return GsonBuilder().create().fromJson(text, Reaction::class.java)
+        } catch (ignore: Exception) {
+        }
+
+        // If that fails, try to decode it in the legacy form.
+        return Reaction(
+            reference = content.parametersMap["reference"] ?: "",
+            action = content.parametersMap["action"]?.let { ReactionAction.valueOf(it) }!!,
+            schema = content.parametersMap["schema"]?.let { ReactionSchema.valueOf(it) }!!,
+            content = text,
+        )
     }
 }