diff --git a/build.sh b/build.sh
index 20aefbd..067ec24 100755
--- a/build.sh
+++ b/build.sh
@@ -22,12 +22,14 @@ case ${1} in
 			log_msg fail "Error: unknown build script specified.";
 			exec cat build.usage;
 		fi;
-		for __ in $(split , "${ARG_RESTART_SCRIPT_AT}"); do
-			if ! match_list "${VALID_BUILD_LEVELS}" , "${__}"; then
-				log_msg fail "Error: unknown build level specified.";
-				exec cat build.usage;
-			fi;
-		done;
+		if [ "${ARG_RESTART_SCRIPT_AT}" != diff ]; then
+			for __ in $(split , "${ARG_RESTART_SCRIPT_AT}"); do
+				if ! match_list "${VALID_BUILD_LEVELS}" , "${__}"; then
+					log_msg fail "Error: unknown build level specified.";
+					exec cat build.usage;
+				fi;
+			done;
+		fi;
 	else
 		ARG_RESTART_SCRIPT="${2}"; ARG_RESTART_SCRIPT_AT=ALL;
 	fi; shift; ;;
diff --git a/build.usage b/build.usage
index 2048aec..624f66c 100644
--- a/build.usage
+++ b/build.usage
@@ -1,5 +1,5 @@
 usage: ./build.sh [-a nt32|nt64] [-b debug|release] [-c] [-h] [-i level.name.build]
-                  [-r ALL|level.name.build[:step]] [-t[.gz|.bz2|.xz] [-x]
+                  [-r ALL|level.name.build[:diff|:step[,...]]] [-t[.gz|.bz2|.xz] [-x]
         -a nt32|nt64           Selects 32-bit or 64-bit architecture; defaults to nt64.
         -b debug|release       Selects debug or release build; defaults to debug.
                                This currently only controls CFLAGS.
@@ -8,11 +8,13 @@ usage: ./build.sh [-a nt32|nt64] [-b debug|release] [-c] [-h] [-i level.name.bui
         -i level.name.build    Insert link to pkg.build for the specified build script.
                                All consecutive scripts with higher build levels will
                                be renamed automatically.
-        -r ALL|level.name.build[:step]
+        -r ALL|level.name.build[:step[,...]]
                                Restart all or the specified build script(s) completely
                                or at the optionally specified build step. Currently defined
-                               build steps are: fetch extract build_dir autoconf patch configure
-                               clean build install.
+                               build steps are: fetch extract build_dir autoconf patch
+                               configure clean build install.
+        -r level.name.build:diff
+                               Automatically produce diff(1).
         -t[.gz|.bz2|.xz]       Produce binary distribution and source tarballs containing ${PREFIX}
                                sans ${WORKDIR} and ${PREFIX}/src/midipix_build and ${WORKDIR} sans top-
                                level regular files at the end of a build with zero failures. The
diff --git a/pkg.build b/pkg.build
index 03309d8..6d44e3a 100644
--- a/pkg.build
+++ b/pkg.build
@@ -3,6 +3,21 @@
 #
 
 parse_with_pkg_name ${SCRIPT_FNAME%[0-9][0-9]*} ${2} ${PKG_BUILD_NAMES};
+if [ "${ARG_RESTART_SCRIPT_AT}" = diff ]; then
+	printf "" > ${MIDIPIX_BUILD_PWD}/${PKG_SUBDIR}.local.patch.new;
+	for __ in $(find ${PKG_SUBDIR} -name \*.orig); do
+		if [ -e ${__%.orig} ]; then
+			echo diff -Nru ${__} ${__%.orig};
+			set +o errexit; diff -Nru ${__} ${__%.orig}	\
+				>> ${MIDIPIX_BUILD_PWD}/${PKG_SUBDIR}.local.patch.new; __=${?}; set -o errexit;
+			if [ ${__} -ge 2 ]; then
+				exit 1;
+			fi;
+		fi;
+	done;
+	ls -la ${MIDIPIX_BUILD_PWD}/${PKG_SUBDIR}.local.patch.new;
+	exit 0;
+fi;
 if ! is_build_script_done fetch; then
 	if test_cmd pkg_${PKG_NAME}_fetch; then
 		pkg_${PKG_NAME}_fetch;