diff --git a/win/win32/vs2010/levcomp.vcxproj b/win/win32/vs2010/levcomp.vcxproj
index 879172ccf..8bcad70dc 100644
--- a/win/win32/vs2010/levcomp.vcxproj
+++ b/win/win32/vs2010/levcomp.vcxproj
@@ -89,7 +89,7 @@
       <Optimization>MaxSpeed</Optimization>
       <InlineFunctionExpansion>OnlyExplicitInline</InlineFunctionExpansion>
       <AdditionalIncludeDirectories>..\include;..\sys\winnt;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>NDEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>NDEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;YY_NO_UNISTD_H;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <StringPooling>true</StringPooling>
       <RuntimeLibrary>MultiThreaded</RuntimeLibrary>
       <FunctionLevelLinking>true</FunctionLevelLinking>
@@ -185,7 +185,7 @@ chdir ..\build
       <Optimization>MaxSpeed</Optimization>
       <InlineFunctionExpansion>OnlyExplicitInline</InlineFunctionExpansion>
       <AdditionalIncludeDirectories>..\include;..\sys\winnt;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>NDEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>NDEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;YY_NO_UNISTD_H;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <StringPooling>true</StringPooling>
       <RuntimeLibrary>MultiThreaded</RuntimeLibrary>
       <FunctionLevelLinking>true</FunctionLevelLinking>
@@ -279,7 +279,7 @@ chdir ..\build
     <ClCompile>
       <Optimization>Disabled</Optimization>
       <AdditionalIncludeDirectories>..\include;..\sys\winnt;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>_DEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;_CRT_SECURE_NO_DEPRECATE;_SCL_SECURE_NO_DEPRECATE;_CRT_NONSTDC_NO_DEPRECATE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>_DEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;_CRT_SECURE_NO_DEPRECATE;_SCL_SECURE_NO_DEPRECATE;_CRT_NONSTDC_NO_DEPRECATE;YY_NO_UNISTD_H;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <MinimalRebuild>true</MinimalRebuild>
       <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
       <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
@@ -376,7 +376,7 @@ chdir ..\build
     <ClCompile>
       <Optimization>Disabled</Optimization>
       <AdditionalIncludeDirectories>..\include;..\sys\winnt;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>_DEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;_CRT_SECURE_NO_DEPRECATE;_SCL_SECURE_NO_DEPRECATE;_CRT_NONSTDC_NO_DEPRECATE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>_DEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;_CRT_SECURE_NO_DEPRECATE;_SCL_SECURE_NO_DEPRECATE;_CRT_NONSTDC_NO_DEPRECATE;YY_NO_UNISTD_H;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
       <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
       <PrecompiledHeaderOutputFile>.\Debug/levcomp.pch</PrecompiledHeaderOutputFile>
@@ -566,4 +566,4 @@ chdir ..\build
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
   </ImportGroup>
-</Project>
\ No newline at end of file
+</Project>
diff --git a/win/win32/vs2013/levcomp.vcxproj b/win/win32/vs2013/levcomp.vcxproj
index a828de3c6..4ea54170d 100644
--- a/win/win32/vs2013/levcomp.vcxproj
+++ b/win/win32/vs2013/levcomp.vcxproj
@@ -91,7 +91,7 @@
       <Optimization>MaxSpeed</Optimization>
       <InlineFunctionExpansion>OnlyExplicitInline</InlineFunctionExpansion>
       <AdditionalIncludeDirectories>..\include;..\sys\winnt;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>NDEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>NDEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;YY_NO_UNISTD_H;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <StringPooling>true</StringPooling>
       <RuntimeLibrary>MultiThreaded</RuntimeLibrary>
       <FunctionLevelLinking>true</FunctionLevelLinking>
@@ -189,7 +189,7 @@ chdir ..\build
       <Optimization>MaxSpeed</Optimization>
       <InlineFunctionExpansion>OnlyExplicitInline</InlineFunctionExpansion>
       <AdditionalIncludeDirectories>..\include;..\sys\winnt;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>NDEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>NDEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;YY_NO_UNISTD_H;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <StringPooling>true</StringPooling>
       <RuntimeLibrary>MultiThreaded</RuntimeLibrary>
       <FunctionLevelLinking>true</FunctionLevelLinking>
@@ -285,7 +285,7 @@ chdir ..\build
     <ClCompile>
       <Optimization>Disabled</Optimization>
       <AdditionalIncludeDirectories>..\include;..\sys\winnt;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>_DEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;_CRT_SECURE_NO_DEPRECATE;_SCL_SECURE_NO_DEPRECATE;_CRT_NONSTDC_NO_DEPRECATE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>_DEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;_CRT_SECURE_NO_DEPRECATE;_SCL_SECURE_NO_DEPRECATE;_CRT_NONSTDC_NO_DEPRECATE;YY_NO_UNISTD_H;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <MinimalRebuild>true</MinimalRebuild>
       <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
       <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
@@ -385,7 +385,7 @@ chdir ..\build
     <ClCompile>
       <Optimization>Disabled</Optimization>
       <AdditionalIncludeDirectories>..\include;..\sys\winnt;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>_DEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;_CRT_SECURE_NO_DEPRECATE;_SCL_SECURE_NO_DEPRECATE;_CRT_NONSTDC_NO_DEPRECATE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>_DEBUG;WIN32;_CONSOLE;WIN32CON;DLB;MSWIN_GRAPHICS;_CRT_SECURE_NO_DEPRECATE;_SCL_SECURE_NO_DEPRECATE;_CRT_NONSTDC_NO_DEPRECATE;YY_NO_UNISTD_H;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
       <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
       <PrecompiledHeaderOutputFile>.\Debug/levcomp.pch</PrecompiledHeaderOutputFile>
@@ -578,4 +578,4 @@ chdir ..\build
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
   </ImportGroup>
-</Project>
\ No newline at end of file
+</Project>