Improve exception text. Closes issue 13811.
diff --git a/Python/formatter_unicode.c b/Python/formatter_unicode.c
index 12b880d..db6364f 100644
--- a/Python/formatter_unicode.c
+++ b/Python/formatter_unicode.c
@@ -241,8 +241,8 @@
     /* Finally, parse the type field. */
 
     if (end-pos > 1) {
-        /* More than one char remain, invalid conversion spec. */
-        PyErr_Format(PyExc_ValueError, "Invalid conversion specification");
+        /* More than one char remain, invalid format specifier. */
+        PyErr_Format(PyExc_ValueError, "Invalid format specifier");
         return 0;
     }