diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9f0f5eea8..382a3ebe1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,10 +7,11 @@ on:
       - '!master'
 
 env:
-  BUILDER_VERSION: v0.3.1
+  BUILDER_VERSION: v0.5.3
   BUILDER_HOST: https://d19elf31gohf1l.cloudfront.net
   PACKAGE_NAME: aws-c-http
   LINUX_BASE_IMAGE: ubuntu-16-x64
+  RUN: ${{ github.run_id }}-${{ github.run_number }}
 
 jobs:
   linux-compat:
@@ -29,7 +30,7 @@ jobs:
         echo "${{ secrets.GITHUB_TOKEN }}" | docker login docker.pkg.github.com -u awslabs --password-stdin
         export DOCKER_IMAGE=docker.pkg.github.com/awslabs/aws-crt-builder/aws-crt-${{ matrix.image }}:${{ env.BUILDER_VERSION }}
         docker pull $DOCKER_IMAGE
-        docker run --env GITHUB_REF $DOCKER_IMAGE -p ${{ env.PACKAGE_NAME }} build manylinux-default-default-default-default
+        docker run --env GITHUB_REF $DOCKER_IMAGE build -p ${{ env.PACKAGE_NAME }} downstream
 
   al2:
     runs-on: ubuntu-latest
@@ -40,7 +41,7 @@ jobs:
         echo "${{ secrets.GITHUB_TOKEN }}" | docker login docker.pkg.github.com -u awslabs --password-stdin
         export DOCKER_IMAGE=docker.pkg.github.com/awslabs/aws-crt-builder/aws-crt-al2-x64:${{ env.BUILDER_VERSION }}
         docker pull $DOCKER_IMAGE
-        docker run --env GITHUB_REF $DOCKER_IMAGE -p ${{ env.PACKAGE_NAME }} build al2-default-default-default-default-downstream
+        docker run --env GITHUB_REF $DOCKER_IMAGE build -p ${{ env.PACKAGE_NAME }} downstream
       
   clang-compat:
     runs-on: ubuntu-latest
@@ -54,7 +55,7 @@ jobs:
         echo "${{ secrets.GITHUB_TOKEN }}" | docker login docker.pkg.github.com -u awslabs --password-stdin
         export DOCKER_IMAGE=docker.pkg.github.com/awslabs/aws-crt-builder/aws-crt-${{ env.LINUX_BASE_IMAGE }}:${{ env.BUILDER_VERSION }}
         docker pull $DOCKER_IMAGE
-        docker run --env GITHUB_REF $DOCKER_IMAGE -p ${{ env.PACKAGE_NAME }} build linux-clang-${{ matrix.version }}-linux-x64
+        docker run --env GITHUB_REF $DOCKER_IMAGE build -p ${{ env.PACKAGE_NAME }} --compiler=clang-${{ matrix.version }}
 
   gcc-compat:
     runs-on: ubuntu-latest
@@ -68,23 +69,40 @@ jobs:
         echo "${{ secrets.GITHUB_TOKEN }}" | docker login docker.pkg.github.com -u awslabs --password-stdin
         export DOCKER_IMAGE=docker.pkg.github.com/awslabs/aws-crt-builder/aws-crt-${{ env.LINUX_BASE_IMAGE }}:${{ env.BUILDER_VERSION }}
         docker pull $DOCKER_IMAGE
-        docker run --env GITHUB_REF $DOCKER_IMAGE -p ${{ env.PACKAGE_NAME }} build linux-gcc-${{ matrix.version }}-linux-x64
+        docker run --env GITHUB_REF $DOCKER_IMAGE build -p ${{ env.PACKAGE_NAME }} --compiler=gcc-${{ matrix.version }}
 
   windows:
     runs-on: windows-latest
     steps:
     - name: Build ${{ env.PACKAGE_NAME }} + consumers
       run: |
-        python -c "from urllib.request import urlretrieve; urlretrieve('${{ env.BUILDER_HOST }}/${{ env.BUILDER_VERSION }}/builder', 'builder.pyz')"
-        python builder.pyz -p ${{ env.PACKAGE_NAME }} build
+        python -c "from urllib.request import urlretrieve; urlretrieve('${{ env.BUILDER_HOST }}/${{ env.BUILDER_VERSION }}/builder.pyz?run=${{ env.RUN }}', 'builder.pyz')"
+        python builder.pyz build -p ${{ env.PACKAGE_NAME }}
+
+  windows-vc14:
+    runs-on: windows-latest
+    strategy:
+      matrix:
+        arch: [x86, x64]
+    steps:
+    - uses: ilammy/msvc-dev-cmd@v1
+      with:
+        toolset: 14.0
+        arch: ${{ matrix.arch }}
+        uwp: false
+        spectre: true
+    - name: Build ${{ env.PACKAGE_NAME }} + consumers
+      run: |
+        python -c "from urllib.request import urlretrieve; urlretrieve('${{ env.BUILDER_HOST }}/${{ env.BUILDER_VERSION }}/builder.pyz?run=${{ env.RUN }}', 'builder.pyz')"
+        python builder.pyz build -p ${{ env.PACKAGE_NAME }}
 
   osx:
     runs-on: macos-latest
     steps:
     - name: Build ${{ env.PACKAGE_NAME }} + consumers
       run: |
-        python3 -c "from urllib.request import urlretrieve; urlretrieve('${{ env.BUILDER_HOST }}/${{ env.BUILDER_VERSION }}/builder', 'builder')"
+        python3 -c "from urllib.request import urlretrieve; urlretrieve('${{ env.BUILDER_HOST }}/${{ env.BUILDER_VERSION }}/builder.pyz?run=${{ env.RUN }}', 'builder')"
         chmod a+x builder
-        ./builder -p ${{ env.PACKAGE_NAME }} build default-downstream
+        ./builder build -p ${{ env.PACKAGE_NAME }} downstream
 
         
diff --git a/source/hpack.c b/source/hpack.c
index 79bae1221..e859162c6 100644
--- a/source/hpack.c
+++ b/source/hpack.c
@@ -1147,7 +1147,7 @@ int aws_hpack_decode(
                     HPACK_LOG(ERROR, context, "Dynamic table update size is absurdly large");
                     return aws_raise_error(AWS_ERROR_HTTP_COMPRESSION);
                 }
-                size_t size = *size64;
+                size_t size = (size_t)*size64;
 
                 HPACK_LOGF(TRACE, context, "Dynamic table size update %zu", size);
                 if (aws_hpack_resize_dynamic_table(context, size)) {