diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/DocumentMemberSerVisitor.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/DocumentMemberSerVisitor.java
index 1f6cd08b9e6..aef7283c753 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/DocumentMemberSerVisitor.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/DocumentMemberSerVisitor.java
@@ -17,8 +17,6 @@
 
 import software.amazon.smithy.codegen.core.CodegenException;
 import software.amazon.smithy.codegen.core.Symbol;
-import software.amazon.smithy.model.knowledge.HttpBinding.Location;
-import software.amazon.smithy.model.knowledge.HttpBindingIndex;
 import software.amazon.smithy.model.shapes.BigDecimalShape;
 import software.amazon.smithy.model.shapes.BigIntegerShape;
 import software.amazon.smithy.model.shapes.BlobShape;
@@ -43,6 +41,7 @@
 import software.amazon.smithy.model.shapes.StructureShape;
 import software.amazon.smithy.model.shapes.TimestampShape;
 import software.amazon.smithy.model.shapes.UnionShape;
+import software.amazon.smithy.model.traits.TimestampFormatTrait;
 import software.amazon.smithy.model.traits.TimestampFormatTrait.Format;
 import software.amazon.smithy.typescript.codegen.TypeScriptDependency;
 import software.amazon.smithy.typescript.codegen.integration.ProtocolGenerator.GenerationContext;
@@ -234,8 +233,9 @@ public final String memberShape(MemberShape shape) {
 
     @Override
     public String timestampShape(TimestampShape shape) {
-        HttpBindingIndex httpIndex = HttpBindingIndex.of(context.getModel());
-        Format format = httpIndex.determineTimestampFormat(shape, Location.DOCUMENT, defaultTimestampFormat);
+        Format format = shape.getTrait(TimestampFormatTrait.class)
+                .map(trait -> Format.fromString(trait.getValue()))
+                .orElse(defaultTimestampFormat);
         return HttpProtocolGeneratorUtils.getTimestampInputParam(context, dataSource, shape, format);
     }
 
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/knowledge/SerdeElisionIndex.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/knowledge/SerdeElisionIndex.java
index 30028eaff41..b8850183400 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/knowledge/SerdeElisionIndex.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/knowledge/SerdeElisionIndex.java
@@ -18,6 +18,7 @@
 import software.amazon.smithy.model.traits.MediaTypeTrait;
 import software.amazon.smithy.model.traits.SparseTrait;
 import software.amazon.smithy.model.traits.StreamingTrait;
+import software.amazon.smithy.model.traits.Trait;
 import software.amazon.smithy.utils.MapUtils;
 
 /**
@@ -28,7 +29,7 @@
  */
 public class SerdeElisionIndex implements KnowledgeIndex {
     private final Map<ShapeId, Boolean> elisionBinding = new HashMap<>();
-    private final Map<String, Class> mutatingTraits = MapUtils.of(
+    private final Map<String, Class<? extends Trait>> mutatingTraits = MapUtils.of(
             "jsonName", JsonNameTrait.class,
             "streaming", StreamingTrait.class,
             "mediaType", MediaTypeTrait.class,
@@ -58,7 +59,7 @@ private boolean canBeElided(Shape shape, Model model) {
     }
 
     private boolean hasMutatingTraits(Shape shape, Model model) {
-        for (Map.Entry<String, Class> entry : mutatingTraits.entrySet()) {
+        for (Map.Entry<String, Class<? extends Trait>> entry : mutatingTraits.entrySet()) {
             if (shape.hasTrait(entry.getValue())) {
                 return true;
             }