diff --git a/coil-core/src/androidMain/kotlin/coil3/memory/MemoryCacheService.kt b/coil-core/src/androidMain/kotlin/coil3/memory/MemoryCacheService.kt
index d18f8a7cf1..d349b6a1d2 100644
--- a/coil-core/src/androidMain/kotlin/coil3/memory/MemoryCacheService.kt
+++ b/coil-core/src/androidMain/kotlin/coil3/memory/MemoryCacheService.kt
@@ -1,24 +1,8 @@
 package coil3.memory
 
-import coil3.memory.MemoryCacheService.Companion.EXTRA_TRANSFORMATION_INDEX
-import coil3.memory.MemoryCacheService.Companion.EXTRA_TRANSFORMATION_SIZE
 import coil3.request.ImageRequest
-import coil3.request.Options
 import coil3.request.transformations
-import coil3.util.forEachIndexedIndices
 
-internal actual fun createComplexMemoryCacheKeyExtras(
-    request: ImageRequest,
-    options: Options,
-): Map<String, String> {
-    var memoryCacheKeyExtras = request.memoryCacheKeyExtras
-    if (request.transformations.isNotEmpty()) {
-        val mutableMemoryCacheKeyExtras = memoryCacheKeyExtras.toMutableMap()
-        request.transformations.forEachIndexedIndices { index, transformation ->
-            mutableMemoryCacheKeyExtras[EXTRA_TRANSFORMATION_INDEX + index] = transformation.cacheKey
-        }
-        mutableMemoryCacheKeyExtras[EXTRA_TRANSFORMATION_SIZE] = options.size.toString()
-        memoryCacheKeyExtras = mutableMemoryCacheKeyExtras
-    }
-    return memoryCacheKeyExtras
+internal actual fun ImageRequest.needsSizeInCacheKey(): Boolean {
+    return transformations.isNotEmpty()
 }
diff --git a/coil-core/src/androidMain/kotlin/coil3/request/imageRequests.android.kt b/coil-core/src/androidMain/kotlin/coil3/request/imageRequests.android.kt
index 51e7387f62..47dd97f43d 100644
--- a/coil-core/src/androidMain/kotlin/coil3/request/imageRequests.android.kt
+++ b/coil-core/src/androidMain/kotlin/coil3/request/imageRequests.android.kt
@@ -53,6 +53,10 @@ fun ImageRequest.Builder.transformations(vararg transformations: Transformation)
 
 fun ImageRequest.Builder.transformations(transformations: List<Transformation>) = apply {
     extras[transformationsKey] = transformations.toImmutableList()
+
+    var index = 0
+    val memoryCacheKey = transformations.joinToString { "${++index}:${it.cacheKey}" }
+    memoryCacheKeyExtra("coil#transformations", memoryCacheKey)
 }
 
 val ImageRequest.transformations: List<Transformation>
diff --git a/coil-core/src/androidUnitTest/kotlin/coil3/memory/MemoryCacheServiceTest.kt b/coil-core/src/androidUnitTest/kotlin/coil3/memory/MemoryCacheServiceTest.kt
index 8fccf12ce8..2d8bab1605 100644
--- a/coil-core/src/androidUnitTest/kotlin/coil3/memory/MemoryCacheServiceTest.kt
+++ b/coil-core/src/androidUnitTest/kotlin/coil3/memory/MemoryCacheServiceTest.kt
@@ -7,8 +7,7 @@ import coil3.RealImageLoader
 import coil3.asImage
 import coil3.key.Keyer
 import coil3.memory.MemoryCacheService.Companion.EXTRA_IS_SAMPLED
-import coil3.memory.MemoryCacheService.Companion.EXTRA_TRANSFORMATION_INDEX
-import coil3.memory.MemoryCacheService.Companion.EXTRA_TRANSFORMATION_SIZE
+import coil3.memory.MemoryCacheService.Companion.EXTRA_SIZE
 import coil3.request.ImageRequest
 import coil3.request.Options
 import coil3.request.RequestService
@@ -25,7 +24,6 @@ import coil3.transform.Transformation
 import coil3.util.SystemCallbacks
 import coil3.util.createBitmap
 import coil3.util.createRequest
-import coil3.util.forEachIndexedIndices
 import coil3.util.toDrawable
 import kotlin.test.assertEquals
 import kotlin.test.assertFalse
@@ -535,10 +533,11 @@ class MemoryCacheServiceTest : RobolectricTest() {
     ): MemoryCache.Key {
         val extras = memoryCacheKeyExtras.toMutableMap()
         if (transformations.isNotEmpty()) {
-            transformations.forEachIndexedIndices { index, transformation ->
-                extras[EXTRA_TRANSFORMATION_INDEX + index] = transformation.cacheKey
-            }
-            extras[EXTRA_TRANSFORMATION_SIZE] = size.toString()
+            extras += ImageRequest.Builder(context)
+                .transformations(transformations)
+                .build()
+                .memoryCacheKeyExtras
+            extras[EXTRA_SIZE] = size.toString()
         }
         return MemoryCache.Key(key, extras)
     }
diff --git a/coil-core/src/commonMain/kotlin/coil3/memory/MemoryCacheService.kt b/coil-core/src/commonMain/kotlin/coil3/memory/MemoryCacheService.kt
index 9d83f50a32..8fa1f58ed4 100644
--- a/coil-core/src/commonMain/kotlin/coil3/memory/MemoryCacheService.kt
+++ b/coil-core/src/commonMain/kotlin/coil3/memory/MemoryCacheService.kt
@@ -49,7 +49,10 @@ internal class MemoryCacheService(
         }
 
         // Else, create a memory cache key with all extras.
-        val extras = createComplexMemoryCacheKeyExtras(request, options)
+        val extras = request.memoryCacheKeyExtras.toMutableMap()
+        if (request.needsSizeInCacheKey()) {
+            extras[EXTRA_SIZE] = options.size.toString()
+        }
         return MemoryCache.Key(key, extras)
     }
 
@@ -111,7 +114,7 @@ internal class MemoryCacheService(
         // The requested dimensions must match the transformation size exactly if it is present.
         // Unlike standard, requests we can't assume transformed bitmaps for the same image have
         // the same aspect ratio.
-        val transformationSize = cacheKey.extras[EXTRA_TRANSFORMATION_SIZE]
+        val transformationSize = cacheKey.extras[EXTRA_SIZE]
         if (transformationSize != null) {
             // 'Size.toString' is safe to use to determine equality.
             return transformationSize == size.toString()
@@ -219,14 +222,10 @@ internal class MemoryCacheService(
 
     companion object {
         private const val TAG = "MemoryCacheService"
-        internal const val EXTRA_TRANSFORMATION_INDEX = "coil#transformation_"
-        internal const val EXTRA_TRANSFORMATION_SIZE = "coil#transformation_size"
+        internal const val EXTRA_SIZE = "coil#size"
         internal const val EXTRA_IS_SAMPLED = "coil#is_sampled"
         internal const val EXTRA_DISK_CACHE_KEY = "coil#disk_cache_key"
     }
 }
 
-internal expect fun createComplexMemoryCacheKeyExtras(
-    request: ImageRequest,
-    options: Options,
-): Map<String, String>
+internal expect fun ImageRequest.needsSizeInCacheKey(): Boolean
diff --git a/coil-core/src/nonAndroidMain/kotlin/coil3/memory/MemoryCacheService.kt b/coil-core/src/nonAndroidMain/kotlin/coil3/memory/MemoryCacheService.kt
index c16da99423..6b925dce63 100644
--- a/coil-core/src/nonAndroidMain/kotlin/coil3/memory/MemoryCacheService.kt
+++ b/coil-core/src/nonAndroidMain/kotlin/coil3/memory/MemoryCacheService.kt
@@ -1,11 +1,5 @@
 package coil3.memory
 
 import coil3.request.ImageRequest
-import coil3.request.Options
 
-internal actual fun createComplexMemoryCacheKeyExtras(
-    request: ImageRequest,
-    options: Options,
-): Map<String, String> {
-    return request.memoryCacheKeyExtras
-}
+internal actual fun ImageRequest.needsSizeInCacheKey() = false
diff --git a/samples/view/src/main/java/sample/view/MainActivity.kt b/samples/view/src/main/java/sample/view/MainActivity.kt
index 0fcd174694..0a919f6719 100644
--- a/samples/view/src/main/java/sample/view/MainActivity.kt
+++ b/samples/view/src/main/java/sample/view/MainActivity.kt
@@ -12,6 +12,8 @@ import androidx.lifecycle.lifecycleScope
 import androidx.recyclerview.widget.StaggeredGridLayoutManager
 import androidx.recyclerview.widget.StaggeredGridLayoutManager.VERTICAL
 import coil3.load
+import coil3.request.transformations
+import coil3.transform.CircleCropTransformation
 import kotlinx.coroutines.launch
 import sample.common.AndroidMainViewModel
 import sample.common.AssetType
@@ -70,6 +72,9 @@ class MainActivity : AppCompatActivity() {
                 binding.detail.isVisible = true
                 binding.detail.load(screen.image.uri) {
                     placeholderMemoryCacheKey(screen.placeholder)
+                    transformations(
+                        CircleCropTransformation()
+                    )
                     extras(screen.image.extras)
                 }
             }