diff --git a/build/nsis.envvarupdate.nsh b/build/nsis.envvarupdate.nsh
index 9c3ecbe337..95c2f1f639 100644
--- a/build/nsis.envvarupdate.nsh
+++ b/build/nsis.envvarupdate.nsh
@@ -43,7 +43,7 @@
   !ifndef Un${StrFuncName}_INCLUDED
     ${Un${StrFuncName}}
   !endif
-  !define un.${StrFuncName} "${Un${StrFuncName}}"
+  !define un.${StrFuncName} '${Un${StrFuncName}}'
 !macroend
 
 !insertmacro _IncludeStrFunction StrTok