diff --git a/FSharpBuild.Directory.Build.targets b/FSharpBuild.Directory.Build.targets
index 742f43fb3f5..d87d68d36c7 100644
--- a/FSharpBuild.Directory.Build.targets
+++ b/FSharpBuild.Directory.Build.targets
@@ -22,7 +22,7 @@
     <MakeDir
       Directories="$(IntermediateOutputPath)"
       Condition="!Exists('$(IntermediateOutputPath)')" />
-    <WriteLinesToFile File="$(__TargetFilePath)" Lines="$(_ReplacementText)" Overwrite="true" />
+    <WriteLinesToFile File="$(__TargetFilePath)" Lines="$(_ReplacementText)" Overwrite="true" WriteOnlyWhenDifferent="true" />
 
     <!-- Make sure it will get cleaned  -->
     <ItemGroup >
@@ -51,7 +51,7 @@
     <MakeDir
       Directories="$(IntermediateOutputPath)"
       Condition="!Exists('$(IntermediateOutputPath)')" />
-    <WriteLinesToFile File="$(IntermediateOutputPath)buildproperties.fs" Lines="@(_BuildPropertyLines)" Overwrite="true" />
+    <WriteLinesToFile File="$(IntermediateOutputPath)buildproperties.fs" Lines="@(_BuildPropertyLines)" Overwrite="true" WriteOnlyWhenDifferent="true" />
 
     <!-- Make sure it will get cleaned  -->
     <ItemGroup>
diff --git a/fcs/Directory.Build.targets b/fcs/Directory.Build.targets
index ea3d9bd8c42..19b6fcd667d 100644
--- a/fcs/Directory.Build.targets
+++ b/fcs/Directory.Build.targets
@@ -17,7 +17,7 @@
     <MakeDir
       Directories="$(IntermediateOutputPath)"
       Condition="!Exists('$(IntermediateOutputPath)')" />
-    <WriteLinesToFile File="$(__TargetFilePath)" Lines="$(_ReplacementText)" Overwrite="true" />
+    <WriteLinesToFile File="$(__TargetFilePath)" Lines="$(_ReplacementText)" Overwrite="true" WriteOnlyWhenDifferent="true" />
 
     <!-- Make sure it will get cleaned  -->
     <ItemGroup >
@@ -46,7 +46,7 @@
     <MakeDir
       Directories="$(IntermediateOutputPath)$(ProjectName)"
       Condition="!Exists('$(IntermediateOutputPath)$(ProjectName)')" />
-    <WriteLinesToFile File="$(IntermediateOutputPath)$(ProjectName)\buildproperties.fs" Lines="@(_BuildPropertyLines)" Overwrite="true" />
+    <WriteLinesToFile File="$(IntermediateOutputPath)$(ProjectName)\buildproperties.fs" Lines="@(_BuildPropertyLines)" Overwrite="true"  WriteOnlyWhenDifferent="true" />
 
     <!-- Make sure it will get cleaned  -->
     <ItemGroup>