diff --git a/data/c.m4 b/data/c.m4
index 417ccd21..a60c2d8f 100644
--- a/data/c.m4
+++ b/data/c.m4
@@ -65,7 +65,7 @@ m4_define([b4_ints_in],
 # MIN to MAX (included).
 m4_define([b4_int_type],
 [m4_if(b4_ints_in($@,      [0],   [255]), [1], [unsigned char],
-       b4_ints_in($@,   [-128],   [128]), [1], [signed char],
+       b4_ints_in($@,   [-128],   [127]), [1], [yysigned_char],
 
        b4_ints_in($@,      [0], [65535]), [1], [unsigned short],
        b4_ints_in($@, [-32768], [32767]), [1], [short],