diff --git a/Visual Studio Projects/PDP10.vcproj b/Visual Studio Projects/PDP10.vcproj
index ec50b14c..f9d1b02c 100644
--- a/Visual Studio Projects/PDP10.vcproj	
+++ b/Visual Studio Projects/PDP10.vcproj	
@@ -42,7 +42,7 @@
 				Name="VCCLCompilerTool"
 				Optimization="0"
 				AdditionalIncludeDirectories="./;../;../PDP10/;../PDP11/;../VAX/;../../windows-build/PCRE/include/;../../windows-build/winpcap/Wpdpack/Include;../../windows-build/pthreads;../slirp;../slirp_glue;../slirp_glue/qemu;../slirp_glue/qemu/win32/include"
-				PreprocessorDefinitions="USE_INT64;VM_PDP10;_CRT_NONSTDC_NO_WARNINGS;_CRT_SECURE_NO_WARNINGS;_WINSOCK_DEPRECATED_NO_WARNINGS;SIM_NEED_GIT_COMMIT_ID;HAVE_PCREPOSIX_H;PCRE_STATIC;USE_SHARED;PTW32_STATIC_LIB;USE_READER_THREAD;HAVE_SLIRP_NETWORK;USE_SIMH_SLIRP_DEBUG"
+				PreprocessorDefinitions="USE_INT64;VM_PDP10;_CRT_NONSTDC_NO_WARNINGS;_CRT_SECURE_NO_WARNINGS;_WINSOCK_DEPRECATED_NO_WARNINGS;SIM_NEED_GIT_COMMIT_ID;HAVE_PCREPOSIX_H;PCRE_STATIC;USE_SHARED;PTW32_STATIC_LIB;USE_READER_THREAD;SIM_ASYNCH_IO;HAVE_SLIRP_NETWORK;USE_SIMH_SLIRP_DEBUG"
 				KeepComments="false"
 				MinimalRebuild="true"
 				BasicRuntimeChecks="0"
@@ -126,7 +126,7 @@
 				OmitFramePointers="true"
 				WholeProgramOptimization="true"
 				AdditionalIncludeDirectories="./;../;../PDP10/;../PDP11/;../VAX/;../../windows-build/PCRE/include/;../../windows-build/winpcap/Wpdpack/Include;../../windows-build/pthreads;../slirp;../slirp_glue;../slirp_glue/qemu;../slirp_glue/qemu/win32/include"
-				PreprocessorDefinitions="USE_INT64;VM_PDP10;_CRT_NONSTDC_NO_WARNINGS;_CRT_SECURE_NO_WARNINGS;_WINSOCK_DEPRECATED_NO_WARNINGS;SIM_NEED_GIT_COMMIT_ID;HAVE_PCREPOSIX_H;PCRE_STATIC;USE_SHARED;PTW32_STATIC_LIB;USE_READER_THREAD;HAVE_SLIRP_NETWORK;USE_SIMH_SLIRP_DEBUG"
+				PreprocessorDefinitions="USE_INT64;VM_PDP10;_CRT_NONSTDC_NO_WARNINGS;_CRT_SECURE_NO_WARNINGS;_WINSOCK_DEPRECATED_NO_WARNINGS;SIM_NEED_GIT_COMMIT_ID;HAVE_PCREPOSIX_H;PCRE_STATIC;USE_SHARED;PTW32_STATIC_LIB;USE_READER_THREAD;SIM_ASYNCH_IO;HAVE_SLIRP_NETWORK;USE_SIMH_SLIRP_DEBUG"
 				StringPooling="true"
 				RuntimeLibrary="0"
 				EnableFunctionLevelLinking="true"