--- a/js/src/shell/js.cpp
+++ b/js/src/shell/js.cpp
@@ -393,17 +393,17 @@ SetContextOptions(JSContext *cx)
 }
 
 /*
  * Some UTF-8 files, notably those written using Notepad, have a Unicode
  * Byte-Order-Mark (BOM) as their first character. This is useless (byte-order
  * is meaningless for UTF-8) but causes a syntax error unless we skip it.
  */
 static void
-SkipUTF8BOM(FILE* file, size_t size)
+SkipUTF8BOM(FILE* file)
 {
     if (!js_CStringsAreUTF8)
         return;
 
     int ch1 = fgetc(file);
     int ch2 = fgetc(file);
     int ch3 = fgetc(file);
 
@@ -447,17 +447,17 @@ Process(JSContext *cx, JSObject *obj, ch
             return;
         }
     }
 
     SetContextOptions(cx);
 
     if (!forceTTY && !isatty(fileno(file)))
     {
-        SkipUTF8BOM(file, size);
+        SkipUTF8BOM(file);
 
         /*
          * It's not interactive - just execute it.
          *
          * Support the UNIX #! shell hack; gobble the first line if it starts
          * with '#'.  TODO - this isn't quite compatible with sharp variables,
          * as a legal js program (using sharp variables) might start with '#'.
          * But that would require multi-character lookahead.