diff --git a/test_runner/src/main/kotlin/ftl/gc/GcIosTestMatrix.kt b/test_runner/src/main/kotlin/ftl/gc/GcIosTestMatrix.kt
index 757bc1b96b..69c6932f99 100644
--- a/test_runner/src/main/kotlin/ftl/gc/GcIosTestMatrix.kt
+++ b/test_runner/src/main/kotlin/ftl/gc/GcIosTestMatrix.kt
@@ -15,6 +15,7 @@ import com.google.api.services.testing.model.TestSpecification
 import com.google.api.services.testing.model.ToolResultsHistory
 import ftl.args.IosArgs
 import ftl.ios.Xctestrun
+import ftl.ios.Xctestrun.toByteArray
 import ftl.util.ShardCounter
 import ftl.util.Utils.fatalError
 import ftl.util.Utils.join
@@ -41,7 +42,13 @@ object GcIosTestMatrix {
         val matrixGcsPath = join(gcsBucket, matrixGcsSuffix)
         val methods = args.testShardChunks.elementAt(testShardsIndex)
 
-        val generatedXctestrun = Xctestrun.rewrite(xcTestParsed, methods)
+        // Parameterized tests on iOS don't shard correctly.
+        // Avoid changing Xctestrun file when test shards is 1.
+        val generatedXctestrun = if (args.testShards == 1) {
+            xcTestParsed.toByteArray()
+        } else {
+            Xctestrun.rewrite(xcTestParsed, methods)
+        }
         val xctestrunFileGcsPath = GcStorage.uploadXCTestFile(args, gcsBucket, matrixGcsSuffix, generatedXctestrun)
 
         val iOSXCTest = IosXcTest()
diff --git a/test_runner/src/main/kotlin/ftl/ios/Xctestrun.kt b/test_runner/src/main/kotlin/ftl/ios/Xctestrun.kt
index f7e015bfda..ff2f68db73 100644
--- a/test_runner/src/main/kotlin/ftl/ios/Xctestrun.kt
+++ b/test_runner/src/main/kotlin/ftl/ios/Xctestrun.kt
@@ -106,8 +106,12 @@ object Xctestrun {
             setOnlyTestIdentifiers(testDictionary, methods)
         }
 
+        return rootClone.toByteArray()
+    }
+
+    fun NSDictionary.toByteArray(): ByteArray {
         val out = ByteArrayOutputStream()
-        PropertyListParser.saveAsXML(rootClone, out)
+        PropertyListParser.saveAsXML(this, out)
         return out.toByteArray()
     }
 }
diff --git a/test_runner/src/main/kotlin/ftl/run/AndroidTestRunner.kt b/test_runner/src/main/kotlin/ftl/run/AndroidTestRunner.kt
index 38e26645e8..b5623dded7 100644
--- a/test_runner/src/main/kotlin/ftl/run/AndroidTestRunner.kt
+++ b/test_runner/src/main/kotlin/ftl/run/AndroidTestRunner.kt
@@ -26,13 +26,13 @@ object AndroidTestRunner {
         val apks = resolveApks(androidArgs, runGcsPath)
         val jobs = arrayListOf<Deferred<TestMatrix>>()
         val runCount = androidArgs.repeatTests
-        val deviceCount = androidArgs.testShardChunks.size
+        val shardCount = androidArgs.testShardChunks.size
         val shardCounter = ShardCounter()
         val history = GcToolResults.createToolResultsHistory(androidArgs)
 
         println(GenericTestRunner.beforeRunMessage(androidArgs))
         repeat(runCount) {
-            repeat(deviceCount) { testShardsIndex ->
+            repeat(shardCount) { testShardsIndex ->
                 jobs += async {
                     GcAndroidTestMatrix.build(
                         appApkGcsPath = apks.first,
diff --git a/test_runner/src/main/kotlin/ftl/run/IosTestRunner.kt b/test_runner/src/main/kotlin/ftl/run/IosTestRunner.kt
index e509869425..250071e41c 100644
--- a/test_runner/src/main/kotlin/ftl/run/IosTestRunner.kt
+++ b/test_runner/src/main/kotlin/ftl/run/IosTestRunner.kt
@@ -35,13 +35,13 @@ object IosTestRunner {
 
         val jobs = arrayListOf<Deferred<TestMatrix>>()
         val runCount = iosArgs.repeatTests
-        val deviceCount = iosArgs.testShardChunks.size
+        val shardCount = iosArgs.testShardChunks.size
         val shardCounter = ShardCounter()
         val history = GcToolResults.createToolResultsHistory(iosArgs)
 
         println(beforeRunMessage(iosArgs))
         repeat(runCount) {
-            repeat(deviceCount) { testShardsIndex ->
+            repeat(shardCount) { testShardsIndex ->
                 jobs += async {
                     GcIosTestMatrix.build(
                         iosDeviceList = iosDeviceList,