diff --git a/src/apps/snmp/LwipMibCompiler/CCodeGeneration/CCodeGeneration.csproj b/src/apps/snmp/LwipMibCompiler/CCodeGeneration/CCodeGeneration.csproj
index 639fed7c..06d5075e 100644
--- a/src/apps/snmp/LwipMibCompiler/CCodeGeneration/CCodeGeneration.csproj
+++ b/src/apps/snmp/LwipMibCompiler/CCodeGeneration/CCodeGeneration.csproj
@@ -10,7 +10,7 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>CCodeGeneration</RootNamespace>
     <AssemblyName>CCodeGeneration</AssemblyName>
-    <TargetFrameworkVersion>v4.5.1</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
     <TargetFrameworkProfile />
   </PropertyGroup>
diff --git a/src/apps/snmp/LwipMibCompiler/LwipMibCompiler/LwipMibCompiler.csproj b/src/apps/snmp/LwipMibCompiler/LwipMibCompiler/LwipMibCompiler.csproj
index 6bd94995..694263aa 100644
--- a/src/apps/snmp/LwipMibCompiler/LwipMibCompiler/LwipMibCompiler.csproj
+++ b/src/apps/snmp/LwipMibCompiler/LwipMibCompiler/LwipMibCompiler.csproj
@@ -10,7 +10,7 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>LwipMibCompiler</RootNamespace>
     <AssemblyName>LwipMibCompiler</AssemblyName>
-    <TargetFrameworkVersion>v4.5.1</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
     <TargetFrameworkProfile />
   </PropertyGroup>
diff --git a/src/apps/snmp/LwipMibCompiler/LwipSnmpCodeGeneration/LwipSnmpCodeGeneration.csproj b/src/apps/snmp/LwipMibCompiler/LwipSnmpCodeGeneration/LwipSnmpCodeGeneration.csproj
index de9d02df..f4541c0c 100644
--- a/src/apps/snmp/LwipMibCompiler/LwipSnmpCodeGeneration/LwipSnmpCodeGeneration.csproj
+++ b/src/apps/snmp/LwipMibCompiler/LwipSnmpCodeGeneration/LwipSnmpCodeGeneration.csproj
@@ -10,7 +10,7 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>LwipSnmpCodeGeneration</RootNamespace>
     <AssemblyName>LwipSnmpCodeGeneration</AssemblyName>
-    <TargetFrameworkVersion>v4.5.1</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
     <TargetFrameworkProfile />
   </PropertyGroup>
diff --git a/src/apps/snmp/LwipMibCompiler/MibViewer/MibViewer.csproj b/src/apps/snmp/LwipMibCompiler/MibViewer/MibViewer.csproj
index 96da2506..957c058c 100644
--- a/src/apps/snmp/LwipMibCompiler/MibViewer/MibViewer.csproj
+++ b/src/apps/snmp/LwipMibCompiler/MibViewer/MibViewer.csproj
@@ -10,7 +10,7 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>LwipMibViewer</RootNamespace>
     <AssemblyName>MibViewer</AssemblyName>
-    <TargetFrameworkVersion>v4.5.1</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
     <TargetFrameworkProfile />
   </PropertyGroup>
diff --git a/src/apps/snmp/LwipMibCompiler/SharpSnmpLib/SharpSnmpLib.Mib.csproj b/src/apps/snmp/LwipMibCompiler/SharpSnmpLib/SharpSnmpLib.Mib.csproj
index f1e724cf..2cf86578 100644
--- a/src/apps/snmp/LwipMibCompiler/SharpSnmpLib/SharpSnmpLib.Mib.csproj
+++ b/src/apps/snmp/LwipMibCompiler/SharpSnmpLib/SharpSnmpLib.Mib.csproj
@@ -26,7 +26,7 @@
     <SccProvider>
     </SccProvider>
     <RunSourceAnalysis>False</RunSourceAnalysis>
-    <TargetFrameworkVersion>v4.5.1</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>