itss: Fix a typo

[Andrew Talbot]

Changelog:
    itss: Fix a typo.

diff --git a/dlls/itss/protocol.c b/dlls/itss/protocol.c
index dd30c7d..d7f3f42 100644
--- a/dlls/itss/protocol.c
+++ b/dlls/itss/protocol.c
@@ -216,7 +216,7 @@ static HRESULT WINAPI ITSProtocol_Start(
     res = chm_resolve_object(chm_file, object_name, &chm_object);
     if(res != CHM_RESOLVE_SUCCESS) {
         WARN("Could not resolve chm object\n");
-        HeapFree(GetProcessHeap(), 0, object_name);
+        HeapFree(GetProcessHeap(), 0, file_name);
         chm_close(chm_file);
         return report_result(pOIProtSink, STG_E_FILENOTFOUND);
     }