diff --git a/src/windows/libespeak-ng.vcxproj b/src/windows/libespeak-ng.vcxproj
index d780e705..63ae5870 100644
--- a/src/windows/libespeak-ng.vcxproj
+++ b/src/windows/libespeak-ng.vcxproj
@@ -88,7 +88,7 @@
       <WarningLevel>Level3</WarningLevel>
       <Optimization>Disabled</Optimization>
       <AdditionalIncludeDirectories>$(ProjectDir);$(ProjectDir)/../include;$(ProjectDir)/../include/compat</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>LIBESPEAK_NG_EXPORT;INCLUDE_KLATT;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>LIBESPEAK_NG_EXPORT;INCLUDE_KLATT;INCLUDE_MBROLA;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <ProgramDataBaseFileName>$(IntDir)libespeak-ng.pdb</ProgramDataBaseFileName>
     </ClCompile>
     <Link>
@@ -102,7 +102,7 @@
       </PrecompiledHeader>
       <WarningLevel>Level3</WarningLevel>
       <Optimization>Disabled</Optimization>
-      <PreprocessorDefinitions>LIBESPEAK_NG_EXPORT;INCLUDE_KLATT;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>LIBESPEAK_NG_EXPORT;INCLUDE_KLATT;INCLUDE_MBROLA;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <ProgramDataBaseFileName>$(IntDir)libespeak-ng.pdb</ProgramDataBaseFileName>
     </ClCompile>
     <Link>
@@ -119,7 +119,7 @@
       <FunctionLevelLinking>true</FunctionLevelLinking>
       <IntrinsicFunctions>true</IntrinsicFunctions>
       <AdditionalIncludeDirectories>$(ProjectDir);$(ProjectDir)/../include;$(ProjectDir)/../include/compat</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>LIBESPEAK_NG_EXPORT;INCLUDE_KLATT;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>LIBESPEAK_NG_EXPORT;INCLUDE_KLATT;INCLUDE_MBROLA;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <ProgramDataBaseFileName>$(IntDir)libespeak-ng.pdb</ProgramDataBaseFileName>
     </ClCompile>
     <Link>
@@ -137,7 +137,7 @@
       <Optimization>MaxSpeed</Optimization>
       <FunctionLevelLinking>true</FunctionLevelLinking>
       <IntrinsicFunctions>true</IntrinsicFunctions>
-      <PreprocessorDefinitions>LIBESPEAK_NG_EXPORT;INCLUDE_KLATT;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>LIBESPEAK_NG_EXPORT;INCLUDE_KLATT;INCLUDE_MBROLA;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <ProgramDataBaseFileName>$(IntDir)libespeak-ng.pdb</ProgramDataBaseFileName>
     </ClCompile>
     <Link>