diff --git a/ports/windows/.appveyor.yml b/ports/windows/.appveyor.yml
index 41b554b2d..c1a114a0f 100644
--- a/ports/windows/.appveyor.yml
+++ b/ports/windows/.appveyor.yml
@@ -34,7 +34,7 @@ before_build:
     <?xml version="1.0" encoding="utf-8"?>
     <Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
       <Target Name="Build">
-        <MsBuild BuildInParallel="True" Projects="mpy-cross\mpy-cross.vcxproj;ports\windows\micropython.vcxproj"/>
+        <MsBuild Projects="mpy-cross\mpy-cross.vcxproj;ports\windows\micropython.vcxproj"/>
       </Target>
     </Project>
     "@ | Set-Content build.proj
diff --git a/ports/windows/msvc/genhdr.targets b/ports/windows/msvc/genhdr.targets
index 7d60e08a0..7bd8364a9 100644
--- a/ports/windows/msvc/genhdr.targets
+++ b/ports/windows/msvc/genhdr.targets
@@ -150,7 +150,9 @@ using(var outFile = System.IO.File.CreateText(OutputFile)) {
       <TmpFile>$(QstrGen).tmp</TmpFile>
     </PropertyGroup>
     <Exec Command="$(PyClTool) /nologo /I@(PyIncDirs, ' /I') /D@(PreProcDefs, ' /D') /E $(PyQstrDefs) $(QstrDefs) > $(DestDir)qstrdefs.preprocessed.h"/>
-    <Exec Command="$(PyPython) $(PySrcDir)makeqstrdata.py $(DestDir)qstrdefs.preprocessed.h $(QstrDefsCollected) > $(TmpFile)"/>
+    <!--Because makemanifest.py relies on this file to have all Q() and QCFG() entries.-->
+    <Exec Command="type $(QstrDefsCollected) >> $(DestDir)qstrdefs.preprocessed.h"/>
+    <Exec Command="$(PyPython) $(PySrcDir)makeqstrdata.py $(DestDir)qstrdefs.preprocessed.h > $(TmpFile)"/>
     <MSBuild Projects="$(MSBuildThisFileFullPath)" Targets="CopyFileIfDifferent" Properties="SourceFile=$(TmpFile);DestFile=$(QstrGen)"/>
   </Target>
 
@@ -167,7 +169,7 @@ using(var outFile = System.IO.File.CreateText(OutputFile)) {
     <ItemGroup>
       <ClCompile Include="$(PyBuildDir)frozen_content.c"/>
       <ClCompile>
-        <PreprocessorDefinitions>MICROPY_MODULE_FROZEN_MPY=1;MICROPY_QSTR_EXTRA_POOL=mp_qstr_frozen_const_pool;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+        <PreprocessorDefinitions>MICROPY_MODULE_FROZEN_MPY=1;MICROPY_QSTR_EXTRA_POOL=mp_qstr_frozen_const_pool;MPZ_DIG_SIZE=16;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       </ClCompile>
     </ItemGroup>
     <Exec Command="$(PyPython) $(PyBaseDir)tools\makemanifest.py -v MPY_DIR=$(PyBaseDir) -v MPY_LIB_DIR=$(PyBaseDir)/lib/micropython-lib -v PORT_DIR=$(PyWinDir) -o $(PyBuildDir)frozen_content.c -b $(PyBuildDir) $(FrozenManifest)"/>
diff --git a/ports/windows/variants/dev/mpconfigvariant.props b/ports/windows/variants/dev/mpconfigvariant.props
index 14ce01a81..be1f1ae51 100644
--- a/ports/windows/variants/dev/mpconfigvariant.props
+++ b/ports/windows/variants/dev/mpconfigvariant.props
@@ -1,5 +1,8 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="14.0">
+  <PropertyGroup>
+    <FrozenManifest>$(PyVariantDir)manifest.py</FrozenManifest>
+  </PropertyGroup>
   <ItemDefinitionGroup>
     <ClCompile>
       <PreprocessorDefinitions>%(PreprocessorDefinitions);MICROPY_ROM_TEXT_COMPRESSION=1</PreprocessorDefinitions>