diff --git a/src/common/textfile.cpp b/src/common/textfile.cpp
index 440f4e8f62..4887c4e507 100644
--- a/src/common/textfile.cpp
+++ b/src/common/textfile.cpp
@@ -135,6 +135,7 @@ bool wxTextFile::OnRead(wxMBConv& conv)
 
         str += strbuf;
 #else // ANSI
+        wxUnusedVar(conv);
         buf[nRead] = '\0';
         str += buf;
 #endif // wxUSE_UNICODE/!wxUSE_UNICODE