diff --git a/cf/have-struct-field.m4 b/cf/have-struct-field.m4
index cb9482274..93651adb5 100644
--- a/cf/have-struct-field.m4
+++ b/cf/have-struct-field.m4
@@ -14,7 +14,7 @@ eval "ac_cv_struct_$2_$4=yes",
 eval "ac_cv_struct_$2_$4=no")
 ])
 changequote(, )dnl
-eval "ac_tr_var=HAVE_STRUCT_`echo $2 | tr '[a-z]' '[A-Z]'`_`echo $4 | tr '[a-z]' '[A-Z]'`"
+eval "ac_tr_var=HAVE_STRUCT_[]upcase($2)_[]upcase($4)"
 changequote([, ])dnl
 
 define([foo], [[HAVE_STRUCT_]translit($2, [a-z], [A-Z])[_]translit($4, [a-z], [A-Z])])
diff --git a/cf/need-declaration.m4 b/cf/need-declaration.m4
index 23dfbdc91..7dc5feb34 100644
--- a/cf/need-declaration.m4
+++ b/cf/need-declaration.m4
@@ -14,7 +14,7 @@ eval "ac_cv_var_$3_declaration=yes")
 ])
 
 changequote(, )dnl
-eval "ac_tr_var=NEED_`echo $3 | tr '[a-z]' '[A-Z]'`_DECLARATION"
+eval "ac_tr_var=NEED_[]upcase($3)[]_DECLARATION"
 changequote([, ])dnl
 
 define([foo], [NEED_]translit($3, [a-z], [A-Z])[_DECLARATION])