diff --git a/ide/vs2019/mimalloc-test-api.vcxproj b/ide/vs2019/mimalloc-test-api.vcxproj
new file mode 100644
index 00000000..812a9cb1
--- /dev/null
+++ b/ide/vs2019/mimalloc-test-api.vcxproj
@@ -0,0 +1,155 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Debug|Win32">
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+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|Win32">
+      <Configuration>Release</Configuration>
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+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Debug|x64">
+      <Configuration>Debug</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|x64">
+      <Configuration>Release</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+  </ItemGroup>
+  <PropertyGroup Label="Globals">
+    <VCProjectVersion>15.0</VCProjectVersion>
+    <ProjectGuid>{FFF7958F-750E-4C21-A04D-22707CC66878}</ProjectGuid>
+    <RootNamespace>mimalloc-test-api</RootNamespace>
+    <WindowsTargetPlatformVersion>10.0</WindowsTargetPlatformVersion>
+    <ProjectName>mimalloc-test-api</ProjectName>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
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+    <WholeProgramOptimization>true</WholeProgramOptimization>
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+    <ConfigurationType>Application</ConfigurationType>
+    <UseDebugLibraries>true</UseDebugLibraries>
+    <PlatformToolset>v142</PlatformToolset>
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+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'" Label="Configuration">
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+    <PlatformToolset>v142</PlatformToolset>
+    <WholeProgramOptimization>true</WholeProgramOptimization>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
+  <ImportGroup Label="ExtensionSettings">
+  </ImportGroup>
+  <ImportGroup Label="Shared">
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+  <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
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+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
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+    <OutDir>$(ProjectDir)..\..\out\msvc-$(Platform)\$(Configuration)\</OutDir>
+    <IntDir>$(ProjectDir)..\..\out\msvc-$(Platform)\$(ProjectName)\$(Configuration)\</IntDir>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
+    <OutDir>$(ProjectDir)..\..\out\msvc-$(Platform)\$(Configuration)\</OutDir>
+    <IntDir>$(ProjectDir)..\..\out\msvc-$(Platform)\$(ProjectName)\$(Configuration)\</IntDir>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
+    <OutDir>$(ProjectDir)..\..\out\msvc-$(Platform)\$(Configuration)\</OutDir>
+    <IntDir>$(ProjectDir)..\..\out\msvc-$(Platform)\$(ProjectName)\$(Configuration)\</IntDir>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'">
+    <OutDir>$(ProjectDir)..\..\out\msvc-$(Platform)\$(Configuration)\</OutDir>
+    <IntDir>$(ProjectDir)..\..\out\msvc-$(Platform)\$(ProjectName)\$(Configuration)\</IntDir>
+  </PropertyGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
+    <ClCompile>
+      <WarningLevel>Level3</WarningLevel>
+      <Optimization>Disabled</Optimization>
+      <SDLCheck>true</SDLCheck>
+      <ConformanceMode>true</ConformanceMode>
+      <AdditionalIncludeDirectories>..\..\include</AdditionalIncludeDirectories>
+    </ClCompile>
+    <Link>
+      <SubSystem>Console</SubSystem>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
+    <ClCompile>
+      <WarningLevel>Level3</WarningLevel>
+      <Optimization>Disabled</Optimization>
+      <SDLCheck>true</SDLCheck>
+      <ConformanceMode>true</ConformanceMode>
+      <AdditionalIncludeDirectories>..\..\include</AdditionalIncludeDirectories>
+    </ClCompile>
+    <Link>
+      <SubSystem>Console</SubSystem>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
+    <ClCompile>
+      <WarningLevel>Level3</WarningLevel>
+      <Optimization>MaxSpeed</Optimization>
+      <FunctionLevelLinking>true</FunctionLevelLinking>
+      <IntrinsicFunctions>true</IntrinsicFunctions>
+      <SDLCheck>true</SDLCheck>
+      <ConformanceMode>true</ConformanceMode>
+      <AdditionalIncludeDirectories>..\..\include</AdditionalIncludeDirectories>
+      <PreprocessorDefinitions>%(PreprocessorDefinitions);NDEBUG</PreprocessorDefinitions>
+    </ClCompile>
+    <Link>
+      <EnableCOMDATFolding>true</EnableCOMDATFolding>
+      <OptimizeReferences>true</OptimizeReferences>
+      <SubSystem>Console</SubSystem>
+    </Link>
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+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'">
+    <ClCompile>
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+      <Optimization>MaxSpeed</Optimization>
+      <FunctionLevelLinking>true</FunctionLevelLinking>
+      <IntrinsicFunctions>true</IntrinsicFunctions>
+      <SDLCheck>true</SDLCheck>
+      <ConformanceMode>true</ConformanceMode>
+      <AdditionalIncludeDirectories>..\..\include</AdditionalIncludeDirectories>
+      <PreprocessorDefinitions>%(PreprocessorDefinitions);NDEBUG</PreprocessorDefinitions>
+    </ClCompile>
+    <Link>
+      <EnableCOMDATFolding>true</EnableCOMDATFolding>
+      <OptimizeReferences>true</OptimizeReferences>
+      <SubSystem>Console</SubSystem>
+    </Link>
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+  <ItemGroup>
+    <ClCompile Include="..\..\test\test-api.c">
+    </ClCompile>
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="mimalloc.vcxproj">
+      <Project>{abb5eae7-b3e6-432e-b636-333449892ea6}</Project>
+    </ProjectReference>
+  </ItemGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
+  <ImportGroup Label="ExtensionTargets">
+  </ImportGroup>
+</Project>
diff --git a/ide/vs2019/mimalloc.sln b/ide/vs2019/mimalloc.sln
index aeab6b88..fcb938a4 100644
--- a/ide/vs2019/mimalloc.sln
+++ b/ide/vs2019/mimalloc.sln
@@ -1,7 +1,7 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
-# Visual Studio 15
-VisualStudioVersion = 15.0.28010.2016
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.29709.97
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "mimalloc", "mimalloc.vcxproj", "{ABB5EAE7-B3E6-432E-B636-333449892EA6}"
 EndProject
@@ -13,6 +13,8 @@ Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "mimalloc-override-test", "m
 EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "mimalloc-test-stress", "mimalloc-test-stress.vcxproj", "{FEF7958F-750E-4C21-A04D-22707CC66878}"
 EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "mimalloc-test-api", "mimalloc-test-api.vcxproj", "{FFF7958F-750E-4C21-A04D-22707CC66878}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|x64 = Debug|x64
@@ -61,6 +63,14 @@ Global
 		{FEF7958F-750E-4C21-A04D-22707CC66878}.Release|x64.Build.0 = Release|x64
 		{FEF7958F-750E-4C21-A04D-22707CC66878}.Release|x86.ActiveCfg = Release|Win32
 		{FEF7958F-750E-4C21-A04D-22707CC66878}.Release|x86.Build.0 = Release|Win32
+		{FFF7958F-750E-4C21-A04D-22707CC66878}.Debug|x64.ActiveCfg = Debug|x64
+		{FFF7958F-750E-4C21-A04D-22707CC66878}.Debug|x64.Build.0 = Debug|x64
+		{FFF7958F-750E-4C21-A04D-22707CC66878}.Debug|x86.ActiveCfg = Debug|Win32
+		{FFF7958F-750E-4C21-A04D-22707CC66878}.Debug|x86.Build.0 = Debug|Win32
+		{FFF7958F-750E-4C21-A04D-22707CC66878}.Release|x64.ActiveCfg = Release|x64
+		{FFF7958F-750E-4C21-A04D-22707CC66878}.Release|x64.Build.0 = Release|x64
+		{FFF7958F-750E-4C21-A04D-22707CC66878}.Release|x86.ActiveCfg = Release|Win32
+		{FFF7958F-750E-4C21-A04D-22707CC66878}.Release|x86.Build.0 = Release|Win32
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
diff --git a/src/alloc.c b/src/alloc.c
index 1f053db9..61f34353 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -110,8 +110,8 @@ void _mi_block_zero_init(const mi_page_t* page, void* p, size_t size) {
   mi_assert_internal(p != NULL);
   mi_assert_internal(mi_usable_size(p) >= size); // size can be zero
   mi_assert_internal(_mi_ptr_page(p)==page);
-  if (page->is_zero) {
-    // already zero initialized memory?
+  if (page->is_zero && size > sizeof(mi_block_t)) {
+    // already zero initialized memory
     ((mi_block_t*)p)->next = 0;  // clear the free list pointer
     mi_assert_expensive(mi_mem_is_zero(p, mi_usable_size(p)));
   }