diff --git a/windows/OpenLP.iss.default b/windows/OpenLP.iss.default
index fe5ac87..0543626 100644
--- a/windows/OpenLP.iss.default
+++ b/windows/OpenLP.iss.default
@@ -7,7 +7,7 @@
 #define AppPublisher "OpenLP Developers"
 #define AppURL "http://openlp.org/"
 #define AppExeName "OpenLP.exe"
-#define Arch "%(arch)"
+#define Arch "%(arch)s"
 
 #define FileHandle FileOpen("%(branch)s\dist\OpenLP\.version")
 #define FileLine FileRead(FileHandle)