diff --git a/win32/vs10/gtk3-build-defines.props b/win32/vs10/gtk3-build-defines.props
index 0a20f662d9..490c508daa 100644
--- a/win32/vs10/gtk3-build-defines.props
+++ b/win32/vs10/gtk3-build-defines.props
@@ -9,7 +9,10 @@
     <GtkPrefixDefine>GTK_PREFIX=\"$(GtkDummyPrefix)\"</GtkPrefixDefine>
     <GdkDefines>GDK_COMPILATION;G_LOG_DOMAIN="Gdk"</GdkDefines>
     <GtkIncludedImmodulesDefines>INCLUDE_IM_am_et;INCLUDE_IM_cedilla;INCLUDE_IM_cyrillic_translit;INCLUDE_IM_ime;INCLUDE_IM_inuktitut;INCLUDE_IM_ipa;INCLUDE_IM_multipress;INCLUDE_IM_thai;INCLUDE_IM_ti_er;INCLUDE_IM_ti_et;INCLUDE_IM_viqr</GtkIncludedImmodulesDefines>
-    <GtkDefines>GTK_COMPILATION;G_LOG_DOMAIN="Gtk";GTK_HOST="i686-pc-vs$(VSVer)";GTK_PRINT_BACKENDS="file";GTK_PRINT_BACKEND_ENABLE_UNSUPPORTED;$(GtkIncludedImmodulesDefines);GTK_LIBDIR="$(GtkDummyPrefix)/lib";GTK_DATADIR="$(GtkDummyPrefix)/share";GTK_DATA_PREFIX="$(GtkDummyPrefix)";GTK_SYSCONFDIR="$(GtkDummyPrefix)/etc";MULTIPRESS_CONFDIR="$(GtkDummyPrefix)/etc/gtk-$(ApiVersion)";MULTIPRESS_LOCALEDIR="$(GtkDummyPrefix)/share/locale";GTK_VERSION="$(GtkVersion)/etc";GTK_BINARY_VERSION="$(GtkBinaryVersion)/etc";GDK_DISABLE_DEPRECATED;ISOLATION_AWARE_ENABLED</GtkDefines>
+    <GtkHostMachine Condition="'$(Platform)' == 'Win32'">i686</GtkHostMachine>
+    <GtkHostMachine Condition="'$(Platform)' == 'x64'">x86_64</GtkHostMachine>
+    <GtkHostMachine Condition="'$(Platform)' == 'arm64'">aarch64</GtkHostMachine>
+    <GtkDefines>GTK_COMPILATION;G_LOG_DOMAIN="Gtk";GTK_HOST="$(GtkHostMachine)-pc-vs$(VSVer)";GTK_PRINT_BACKENDS="file";GTK_PRINT_BACKEND_ENABLE_UNSUPPORTED;$(GtkIncludedImmodulesDefines);GTK_LIBDIR="$(GtkDummyPrefix)/lib";GTK_DATADIR="$(GtkDummyPrefix)/share";GTK_DATA_PREFIX="$(GtkDummyPrefix)";GTK_SYSCONFDIR="$(GtkDummyPrefix)/etc";MULTIPRESS_CONFDIR="$(GtkDummyPrefix)/etc/gtk-$(ApiVersion)";MULTIPRESS_LOCALEDIR="$(GtkDummyPrefix)/share/locale";GTK_VERSION="$(GtkVersion)/etc";GTK_BINARY_VERSION="$(GtkBinaryVersion)/etc";GDK_DISABLE_DEPRECATED;ISOLATION_AWARE_ENABLED</GtkDefines>
     <CommonARM64SystemLibs Condition="'$(VisualStudioVersion)|$(Platform)' == '15.0|arm64'">ole32.lib;advapi32.lib;shell32.lib;gdi32.lib</CommonARM64SystemLibs>
     <GtkGdkCommonLibs>pangowin32-1.0.lib;fribidi.lib;imm32.lib;$(CommonARM64SystemLibs)</GtkGdkCommonLibs>
     <GdkAdditionalLibs>winmm.lib;dwmapi.lib;setupapi.lib;$(GtkGdkCommonLibs)</GdkAdditionalLibs>
@@ -62,6 +65,9 @@ nmake -f gtk-introspection-msvc.mak CFG=$(Configuration) PREFIX=$(GlibEtcInstall
     <BuildMacro Include="GtkIncludedImmodulesDefines">
       <Value>$(GtkIncludedImmodulesDefines)</Value>
     </BuildMacro>
+    <BuildMacro Include="GtkHostMachine">
+      <Value>$(GtkHostMachine)</Value>
+    </BuildMacro>
     <BuildMacro Include="GtkDefines">
       <Value>$(GtkDefines)</Value>
     </BuildMacro>
diff --git a/win32/vs9/gtk-3.vcprojin b/win32/vs9/gtk-3.vcprojin
index c17fd45051..547e4216fa 100644
--- a/win32/vs9/gtk-3.vcprojin
+++ b/win32/vs9/gtk-3.vcprojin
@@ -96,7 +96,7 @@
 				Name="VCCLCompilerTool"
 				Optimization="0"
 				AdditionalIncludeDirectories="..\..\gtk;..\..\gdk;..\..\gdk\win32"
-				PreprocessorDefinitions="_DEBUG;G_ENABLE_DEBUG;$(GtkDefines)"
+				PreprocessorDefinitions="_DEBUG;G_ENABLE_DEBUG;$(GtkDefinesX64)"
 				MinimalRebuild="true"
 				BasicRuntimeChecks="3"
 				RuntimeLibrary="3"
@@ -128,7 +128,7 @@
 			<Tool
 				Name="VCCLCompilerTool"
 				AdditionalIncludeDirectories="..\..\gtk;..\..\gdk;..\..\gdk\win32"
-				PreprocessorDefinitions="$(GtkDefines)"
+				PreprocessorDefinitions="$(GtkDefinesX64)"
 				RuntimeLibrary="2"
 				UsePrecompiledHeader="0"
 				WarningLevel="3"
diff --git a/win32/vs9/gtk3-build-defines.vsprops b/win32/vs9/gtk3-build-defines.vsprops
index 8efb6b1574..be5223c84e 100644
--- a/win32/vs9/gtk3-build-defines.vsprops
+++ b/win32/vs9/gtk3-build-defines.vsprops
@@ -43,6 +43,10 @@
 		Name="GtkDefines"
 		Value="GTK_COMPILATION;G_LOG_DOMAIN=\&quot;Gtk\&quot;;GTK_HOST=\&quot;i686-pc-vs$(VSVer)\&quot;;GTK_PRINT_BACKENDS=\&quot;file\&quot;;GTK_PRINT_BACKEND_ENABLE_UNSUPPORTED;$(GtkIncludedImmodulesDefines);GTK_LIBDIR=\&quot;$(GtkDummyPrefix)/lib\&quot;;GTK_DATADIR=\&quot;$(GtkDummyPrefix)/share\&quot;GTK_DATA_PREFIX=\&quot;$(GtkDummyPrefix)\&quot;;GTK_SYSCONFDIR=\&quot;$(GtkDummyPrefix)/etc\&quot;;MULTIPRESS_CONFDIR=\&quot;$(GtkDummyPrefix)/etc/gtk-$(ApiVersion)\&quot;;MULTIPRESS_LOCALEDIR=\&quot;$(GtkDummyPrefix)/share/locale\&quot;;GTK_VERSION=\&quot;$(GtkVersion)/etc\&quot;;GTK_BINARY_VERSION=\&quot;$(GtkBinaryVersion)/etc\&quot;;GDK_DISABLE_DEPRECATED;ISOLATION_AWARE_ENABLED"
 	/>
+	<UserMacro
+		Name="GtkDefinesX64"
+		Value="GTK_COMPILATION;G_LOG_DOMAIN=\&quot;Gtk\&quot;;GTK_HOST=\&quot;x86_64-pc-vs$(VSVer)\&quot;;GTK_PRINT_BACKENDS=\&quot;file\&quot;;GTK_PRINT_BACKEND_ENABLE_UNSUPPORTED;$(GtkIncludedImmodulesDefines);GTK_LIBDIR=\&quot;$(GtkDummyPrefix)/lib\&quot;;GTK_DATADIR=\&quot;$(GtkDummyPrefix)/share\&quot;GTK_DATA_PREFIX=\&quot;$(GtkDummyPrefix)\&quot;;GTK_SYSCONFDIR=\&quot;$(GtkDummyPrefix)/etc\&quot;;MULTIPRESS_CONFDIR=\&quot;$(GtkDummyPrefix)/etc/gtk-$(ApiVersion)\&quot;;MULTIPRESS_LOCALEDIR=\&quot;$(GtkDummyPrefix)/share/locale\&quot;;GTK_VERSION=\&quot;$(GtkVersion)/etc\&quot;;GTK_BINARY_VERSION=\&quot;$(GtkBinaryVersion)/etc\&quot;;GDK_DISABLE_DEPRECATED;ISOLATION_AWARE_ENABLED"
+	/>
 	<UserMacro
 		Name="GtkGdkCommonLibs"
 		Value="pangowin32-1.0.lib fribidi.lib imm32.lib"