diff --git a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
index b2ab970..35ed1fa 100644
--- a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
@@ -1771,16 +1771,16 @@
         }
       }
 
-      Map<Initializer, InitializerInferenceResult> inferenceResults =
-          <Initializer, InitializerInferenceResult>{};
-      for (Initializer initializer in initializers) {
-        inferenceResults[initializer] =
-            typeInferrer.inferInitializer(this, initializer);
-      }
+      List<InitializerInferenceResult> inferenceResults =
+          new List<InitializerInferenceResult>.generate(
+              initializers.length,
+              (index) =>
+                  typeInferrer.inferInitializer(this, initializers[index]),
+              growable: false);
       if (!builder.isExternal) {
-        for (Initializer initializer in initializers) {
-          builder.addInitializer(initializer, this,
-              inferenceResult: inferenceResults[initializer]!);
+        for (int i = 0; i < initializers.length; i++) {
+          builder.addInitializer(initializers[i], this,
+              inferenceResult: inferenceResults[i]);
         }
       }
     }
diff --git a/tools/VERSION b/tools/VERSION
index 99ab702..949b79b 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -27,5 +27,5 @@
 MAJOR 2
 MINOR 17
 PATCH 0
-PRERELEASE 121
+PRERELEASE 122
 PRERELEASE_PATCH 0
\ No newline at end of file