Index: acinclude.m4
===================================================================
--- acinclude.m4
+++ acinclude.m4
@@ -587,7 +587,7 @@
 
 EOF
         # Now generate the symbol file.
-        sed 's/^.* _\?\(.*\)$/extern char \1;/' < "$ac_nlist" >> conftest.c
+        sed 's/^.* _\{0,1\}\(.*\)$/extern char \1;/' < "$ac_nlist" >> conftest.c
 
         cat <<EOF >> conftest.c
 #if defined (__STDC__) && __STDC__
@@ -609,7 +609,7 @@
 changequote([,])dnl
 {
 EOF
-        sed 's/^_\?\(.*\) _\?\(.*\)$/  {"\1", (__ptr_t) \&\2},/' < "$ac_nlist" >> conftest.c
+        sed 's/^_\{0,1\}/\(.*\) _\{0,1\}\(.*\)$/  {"\1", (__ptr_t) \&\2},/' < "$ac_nlist" >> conftest.c
         cat <<\EOF >> conftest.c
   {0, (__ptr_t) 0}
 };