diff --git a/appveyor.yml b/appveyor.yml
index 894445a..5b77579 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -6,7 +6,7 @@ platform:
 - Win32
 shallow_clone: true
 before_build:
-- ps: (Get-Content "C:\Program Files (x86)\Microsoft SDKs\Windows\v7.1A\Include\ntsecapi.h") | %{$_ -replace [Regex]::Escape("RtlDecryptMemory("), "__stdcall RtlDecryptMemory("} | Set-Content "C:\Program Files (x86)\Microsoft SDKs\Windows\v7.1A\Include\ntsecapi.h"
+- ps: (Get-Content "C:\Program Files (x86)\Microsoft SDKs\Windows\v7.1A\Include\ntsecapi.h") | %{$_ -replace "^RtlDecryptMemory\($", "__stdcall RtlDecryptMemory("} | Set-Content "C:\Program Files (x86)\Microsoft SDKs\Windows\v7.1A\Include\ntsecapi.h"
 build:
   parallel: true
   verbosity: normal