diff --git a/build.vc10/dll_mpir_core2/dll_mpir_core2.vcxproj b/build.vc10/dll_mpir_core2/dll_mpir_core2.vcxproj
index 89d33c67..9e0bb541 100644
--- a/build.vc10/dll_mpir_core2/dll_mpir_core2.vcxproj
+++ b/build.vc10/dll_mpir_core2/dll_mpir_core2.vcxproj
@@ -51,7 +51,7 @@ prebuild core2 x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>DLL;_WIN64_ABI</Defines>
+      <Defines>DLL</Defines>
       <IncludePaths>..\..\mpn\x86_64w\</IncludePaths>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
@@ -99,7 +99,7 @@ prebuild core2 x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>DLL;_WIN64_ABI</Defines>
+      <Defines>DLL</Defines>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
       <ObjectFile>$(IntDir)mpn\</ObjectFile>
diff --git a/build.vc10/dll_mpir_k10/dll_mpir_k10.vcxproj b/build.vc10/dll_mpir_k10/dll_mpir_k10.vcxproj
index 33693133..7744593d 100644
--- a/build.vc10/dll_mpir_k10/dll_mpir_k10.vcxproj
+++ b/build.vc10/dll_mpir_k10/dll_mpir_k10.vcxproj
@@ -53,7 +53,7 @@ prebuild k10 x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>DLL;_WIN64_ABI</Defines>
+      <Defines>DLL</Defines>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
       <ObjectFile>$(IntDir)mpn\</ObjectFile>
@@ -101,7 +101,7 @@ prebuild k10 x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>DLL;_WIN64_ABI</Defines>
+      <Defines>DLL</Defines>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
       <ObjectFile>$(IntDir)mpn\</ObjectFile>
diff --git a/build.vc10/dll_mpir_k8/dll_mpir_k8.vcxproj b/build.vc10/dll_mpir_k8/dll_mpir_k8.vcxproj
index cfe8bb7a..a7c6777a 100644
--- a/build.vc10/dll_mpir_k8/dll_mpir_k8.vcxproj
+++ b/build.vc10/dll_mpir_k8/dll_mpir_k8.vcxproj
@@ -52,7 +52,7 @@ prebuild k8 x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>DLL;_WIN64_ABI</Defines>
+      <Defines>DLL</Defines>
       <IncludePaths>..\..\mpn\x86_64w\</IncludePaths>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
@@ -100,7 +100,7 @@ prebuild k8 x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>DLL;_WIN64_ABI</Defines>
+      <Defines>DLL</Defines>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
       <ObjectFile>$(IntDir)mpn\</ObjectFile>
diff --git a/build.vc10/dll_mpir_nehalem/dll_mpir_nehalem.vcxproj b/build.vc10/dll_mpir_nehalem/dll_mpir_nehalem.vcxproj
index 2490f227..14553265 100644
--- a/build.vc10/dll_mpir_nehalem/dll_mpir_nehalem.vcxproj
+++ b/build.vc10/dll_mpir_nehalem/dll_mpir_nehalem.vcxproj
@@ -51,7 +51,7 @@ prebuild nehalem x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>DLL;_WIN64_ABI</Defines>
+      <Defines>DLL</Defines>
       <IncludePaths>..\..\mpn\x86_64w\</IncludePaths>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
@@ -99,7 +99,7 @@ prebuild nehalem x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>DLL;_WIN64_ABI</Defines>
+      <Defines>DLL</Defines>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
       <ObjectFile>$(IntDir)mpn\</ObjectFile>
diff --git a/build.vc10/lib_mpir_core2/lib_mpir_core2.vcxproj b/build.vc10/lib_mpir_core2/lib_mpir_core2.vcxproj
index 5077370a..5ea25f49 100644
--- a/build.vc10/lib_mpir_core2/lib_mpir_core2.vcxproj
+++ b/build.vc10/lib_mpir_core2/lib_mpir_core2.vcxproj
@@ -51,7 +51,8 @@ prebuild core2 x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>_WIN64_ABI</Defines>
+      <Defines>
+      </Defines>
       <IncludePaths>..\..\mpn\x86_64w\</IncludePaths>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
@@ -89,7 +90,8 @@ prebuild core2 x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>_WIN64_ABI</Defines>
+      <Defines>
+      </Defines>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
       <ObjectFile>$(IntDir)mpn\</ObjectFile>
diff --git a/build.vc10/lib_mpir_k10/lib_mpir_k10.vcxproj b/build.vc10/lib_mpir_k10/lib_mpir_k10.vcxproj
index 398f7709..3d10298b 100644
--- a/build.vc10/lib_mpir_k10/lib_mpir_k10.vcxproj
+++ b/build.vc10/lib_mpir_k10/lib_mpir_k10.vcxproj
@@ -52,7 +52,8 @@ prebuild k10 x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>_WIN64_ABI</Defines>
+      <Defines>
+      </Defines>
       <IncludePaths>..\..\mpn\x86_64w\</IncludePaths>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
@@ -90,7 +91,8 @@ prebuild k10 x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>_WIN64_ABI</Defines>
+      <Defines>
+      </Defines>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
       <ObjectFile>$(IntDir)mpn\</ObjectFile>
diff --git a/build.vc10/lib_mpir_k8/lib_mpir_k8.vcxproj b/build.vc10/lib_mpir_k8/lib_mpir_k8.vcxproj
index ae4a041e..f38a1d8a 100644
--- a/build.vc10/lib_mpir_k8/lib_mpir_k8.vcxproj
+++ b/build.vc10/lib_mpir_k8/lib_mpir_k8.vcxproj
@@ -52,7 +52,8 @@ prebuild k8 x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>_WIN64_ABI</Defines>
+      <Defines>
+      </Defines>
       <IncludePaths>..\..\mpn\x86_64w\</IncludePaths>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
@@ -90,7 +91,8 @@ prebuild k8 x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>_WIN64_ABI</Defines>
+      <Defines>
+      </Defines>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
       <ObjectFile>$(IntDir)mpn\</ObjectFile>
diff --git a/build.vc10/lib_mpir_nehalem/lib_mpir_nehalem.vcxproj b/build.vc10/lib_mpir_nehalem/lib_mpir_nehalem.vcxproj
index 2b681ff7..e968ccd0 100644
--- a/build.vc10/lib_mpir_nehalem/lib_mpir_nehalem.vcxproj
+++ b/build.vc10/lib_mpir_nehalem/lib_mpir_nehalem.vcxproj
@@ -52,7 +52,8 @@ prebuild nehalem x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>_WIN64_ABI</Defines>
+      <Defines>
+      </Defines>
       <IncludePaths>..\..\mpn\x86_64w\</IncludePaths>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
@@ -90,7 +91,8 @@ prebuild nehalem x64
       </Command>
     </CustomBuildStep>
     <YASM>
-      <Defines>_WIN64_ABI</Defines>
+      <Defines>
+      </Defines>
       <Debug>true</Debug>
       <ObjectFileName>$(IntDir)mpn\</ObjectFileName>
       <ObjectFile>$(IntDir)mpn\</ObjectFile>