--- a/ipkg-build
+++ b/ipkg-build
@@ -133,7 +133,7 @@ You probably want to chown these to a sy
 	disallowed_filename=`disallowed_field Filename`
 	[ "$?" -ne 0 ] && PKG_ERROR=1
 
-	if echo $pkg | grep '[^a-z0-9.+-]'; then
+	if echo $pkg | grep '[^a-zA-Z0-9_.+-]'; then
 		echo "*** Error: Package name $name contains illegal characters, (other than [a-z0-9.+-])" >&2
 		PKG_ERROR=1;
 	fi
--- a/ipkg-buildpackage
+++ b/ipkg-buildpackage
@@ -69,7 +69,7 @@ pkg_appears_sane_control() {
 	required_field Maintainer >/dev/null
 	required_field Description >/dev/null
 
-	if echo $pkg | grep '[^a-z0-9.+-]'; then
+	if echo $pkg | grep '[^a-zA-Z0-9.+-]'; then
 		echo "ipkg-build: Error: Package name $name contains illegal characters, (other than [a-z0-9.+-])"
 		PKG_ERROR=1;
 	fi
