diff --git a/wrapper/CSharp/wolfssl.vcxproj b/wrapper/CSharp/wolfssl.vcxproj
index 1d142db4b..8ac0fdb72 100644
--- a/wrapper/CSharp/wolfssl.vcxproj
+++ b/wrapper/CSharp/wolfssl.vcxproj
@@ -230,7 +230,7 @@
       <Optimization>MaxSpeed</Optimization>
       <IntrinsicFunctions>true</IntrinsicFunctions>
       <AdditionalIncludeDirectories>./;../../;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>BUILDING_WOLFSSL;WOLFSSL_USER_SETTINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>BUILDING_WOLFSSL;WOLFSSL_DLL;WOLFSSL_USER_SETTINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <RuntimeLibrary>MultiThreadedDLL</RuntimeLibrary>
       <FunctionLevelLinking>true</FunctionLevelLinking>
       <PrecompiledHeader>
@@ -262,7 +262,7 @@
       <Optimization>MaxSpeed</Optimization>
       <IntrinsicFunctions>true</IntrinsicFunctions>
       <AdditionalIncludeDirectories>./;../../;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>BUILDING_WOLFSSL;WOLFSSL_USER_SETTINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>BUILDING_WOLFSSL;WOLFSSL_DLL;WOLFSSL_USER_SETTINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <RuntimeLibrary>MultiThreadedDLL</RuntimeLibrary>
       <FunctionLevelLinking>true</FunctionLevelLinking>
       <PrecompiledHeader>
@@ -453,4 +453,4 @@
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
   </ImportGroup>
-</Project>
+</Project>
\ No newline at end of file