diff --git a/components/codetools/linkscanner.pas b/components/codetools/linkscanner.pas
index 200c7ce23f..0aa8030186 100644
--- a/components/codetools/linkscanner.pas
+++ b/components/codetools/linkscanner.pas
@@ -4198,6 +4198,7 @@ end;
 function TLinkScanner.IfOptDirective: boolean;
 // {$ifopt o+} or {$ifopt o-}
 var Option, c: char;
+  v: String;
 begin
   inc(IfLevel);
   if StoreDirectives then
@@ -4212,7 +4213,8 @@ begin
     if (SrcPos<=SrcLen) then begin
       c:=Src[SrcPos];
       if c in ['+','-'] then begin
-        if (c='-')<>(Values.Variables[CompilerSwitchesNames[Option]]='0') then
+        v:=Values.Variables[CompilerSwitchesNames[Option]];
+        if (c='-')<>((v='0') or (v='')) then
         begin
           SkipTillEndifElse(lssdTillElse);
           exit;