diff --git a/contrib/csri/csri_2008.vcproj b/contrib/csri/csri_2008.vcproj
index fcb92a517..332ce6adb 100644
--- a/contrib/csri/csri_2008.vcproj
+++ b/contrib/csri/csri_2008.vcproj
@@ -50,7 +50,6 @@
 				RuntimeLibrary="3"
 				UsePrecompiledHeader="0"
 				WarningLevel="3"
-				Detect64BitPortabilityProblems="false"
 				DebugInformationFormat="4"
 				CompileAs="1"
 				DisableSpecificWarnings="4996"
@@ -115,7 +114,6 @@
 				RuntimeLibrary="3"
 				UsePrecompiledHeader="0"
 				WarningLevel="3"
-				Detect64BitPortabilityProblems="true"
 				DebugInformationFormat="3"
 				CompileAs="1"
 				DisableSpecificWarnings="4996"
@@ -177,7 +175,6 @@
 				RuntimeLibrary="2"
 				UsePrecompiledHeader="0"
 				WarningLevel="3"
-				Detect64BitPortabilityProblems="false"
 				DebugInformationFormat="3"
 				DisableSpecificWarnings="4996"
 			/>
@@ -239,7 +236,6 @@
 				RuntimeLibrary="2"
 				UsePrecompiledHeader="0"
 				WarningLevel="3"
-				Detect64BitPortabilityProblems="true"
 				DebugInformationFormat="3"
 				DisableSpecificWarnings="4996"
 			/>
diff --git a/contrib/hunspell/src/win_api/libhunspell_2008.vcproj b/contrib/hunspell/src/win_api/libhunspell_2008.vcproj
index bd5de22f0..4a5b368b1 100644
--- a/contrib/hunspell/src/win_api/libhunspell_2008.vcproj
+++ b/contrib/hunspell/src/win_api/libhunspell_2008.vcproj
@@ -53,7 +53,6 @@
 				UsePrecompiledHeader="0"
 				ProgramDataBaseFileName="$(IntDir)\$(ProjectName).pdb"
 				WarningLevel="4"
-				Detect64BitPortabilityProblems="false"
 				DebugInformationFormat="4"
 				DisableSpecificWarnings="4706"
 			/>
@@ -120,7 +119,6 @@
 				UsePrecompiledHeader="0"
 				ProgramDataBaseFileName="$(IntDir)\$(ProjectName).pdb"
 				WarningLevel="4"
-				Detect64BitPortabilityProblems="false"
 				DebugInformationFormat="3"
 				DisableSpecificWarnings="4706"
 			/>
@@ -189,7 +187,6 @@
 				UsePrecompiledHeader="0"
 				ProgramDataBaseFileName="$(IntDir)\$(ProjectName).pdb"
 				WarningLevel="4"
-				Detect64BitPortabilityProblems="false"
 				DebugInformationFormat="0"
 				DisableSpecificWarnings="4706"
 			/>
@@ -261,7 +258,6 @@
 				UsePrecompiledHeader="0"
 				ProgramDataBaseFileName="$(IntDir)\$(ProjectName).pdb"
 				WarningLevel="4"
-				Detect64BitPortabilityProblems="false"
 				DebugInformationFormat="0"
 				DisableSpecificWarnings="4706"
 			/>
diff --git a/contrib/lua51/lua51_vc9.vcproj b/contrib/lua51/lua51_vc9.vcproj
index d322af9da..02b02429d 100644
--- a/contrib/lua51/lua51_vc9.vcproj
+++ b/contrib/lua51/lua51_vc9.vcproj
@@ -51,7 +51,6 @@
 				UsePrecompiledHeader="0"
 				WarningLevel="3"
 				WarnAsError="true"
-				Detect64BitPortabilityProblems="true"
 				DebugInformationFormat="4"
 				CompileAs="2"
 				DisableSpecificWarnings="4996"
@@ -117,7 +116,6 @@
 				UsePrecompiledHeader="0"
 				WarningLevel="3"
 				WarnAsError="false"
-				Detect64BitPortabilityProblems="true"
 				DebugInformationFormat="3"
 				CompileAs="2"
 				DisableSpecificWarnings="4996"
@@ -177,7 +175,6 @@
 				RuntimeLibrary="2"
 				UsePrecompiledHeader="0"
 				WarningLevel="3"
-				Detect64BitPortabilityProblems="true"
 				DebugInformationFormat="3"
 				DisableSpecificWarnings="4996"
 			/>
@@ -237,7 +234,6 @@
 				RuntimeLibrary="2"
 				UsePrecompiledHeader="0"
 				WarningLevel="3"
-				Detect64BitPortabilityProblems="true"
 				DebugInformationFormat="3"
 				DisableSpecificWarnings="4996"
 			/>