diff --git a/components/codetools/basiccodetools.pas b/components/codetools/basiccodetools.pas
index 43966fda31..3fd58562c0 100644
--- a/components/codetools/basiccodetools.pas
+++ b/components/codetools/basiccodetools.pas
@@ -4422,8 +4422,8 @@ function IdentifierPos(Search, Identifier: PChar): PtrInt;
 var
   i: Integer;
 begin
-  if (Search=nil) or (Search^=#0) then exit(-1);
   if Identifier=nil then exit(-1);
+  if (Search=nil) or (Search^=#0) then exit(0);
   Result:=0;
   while (IsIdentChar[Identifier[Result]]) do begin
     if UpChars[Search^]=UpChars[Identifier[Result]] then begin
diff --git a/components/codetools/identcompletiontool.pas b/components/codetools/identcompletiontool.pas
index 07b5d7de35..1fea0c635d 100644
--- a/components/codetools/identcompletiontool.pas
+++ b/components/codetools/identcompletiontool.pas
@@ -637,7 +637,9 @@ begin
       if FExtendedFilter then
         i:=IdentifierPos(PChar(Pointer(Prefix)),PChar(Pointer(CurItem.Identifier)))
       else if ComparePrefixIdent(PChar(Pointer(Prefix)),PChar(Pointer(CurItem.Identifier))) then
-        i:=0;
+        i:=0
+      else
+        i:=-1;
       if i=0 then begin
         {$IFDEF ShowFilteredIdents}
         DebugLn(['::: FILTERED ITEM ',FFilteredList.Count,' ',CurItem.Identifier]);