diff --git a/buildall.sh b/buildall.sh
index 2e443f6..7f72cde 100755
--- a/buildall.sh
+++ b/buildall.sh
@@ -49,16 +49,19 @@ function setup-build-sig {
 	if [ "${2}${3}${4}" = "" ]
 	then
 		t="unset"
+		i="unset"
 	else
 		t=`date --rfc-3339 seconds`
+		i="${v} built by ${u} on ${t}"
 	fi
 
 cat <<-EOF > ${tmp}/manifest.sed
 s/${o}/${v}/g
-s/^ *"build-signature-user" ".*" *\$/\t\t"build-signature-user" "${u}"/
-s/^ *"build-signature-email" ".*" *\$/\t\t"build-signature-email" "${e}"/
-s/^ *"build-signature-timestamp" ".*" *\$/\t\t"build-signature-timestamp" "${t}"/
-s/^ *"build-signature-version" ".*" *\$/\t\t"build-signature-version" "${v}"/
+s/"build-signature-user" *".*"/"build-signature-user" "${u}"/
+s/"build-signature-email" *".*"/"build-signature-email" "${e}"/
+s/"build-signature-timestamp" *".*"/"build-signature-timestamp" "${t}"/
+s/"build-signature-version" *".*"/"build-signature-version" "${v}"/
+s/"Implementation-Version" *".*"/"Implementation-Version" "${i}"/
 EOF
 }
 
@@ -125,7 +128,8 @@ fi
 for dir in mw-*
 do
 	pushd ${dir}
-	
+
+	# Make a temporary directory to keep the work-in-progress files.
 	if [ ! -d "${tmp}" ]
 	then
 		rm -f "${tmp}"
@@ -182,6 +186,16 @@ do
 	lein marg
 	lein install
 	
+	# If we're in the UI project, build the uberwar - and should 
+	# probably deploy it to local Tomcat for test
+	if [ "${dir}" = "mw-ui" -a "${webappsdir}" != "" ]
+	then
+    	lein ring uberwar
+		sudo cp target/microworld.war "${webappsdir}"
+		echo "Deployed new WAR file to local Tomcat at ${webappsdir}"
+	fi
+
+		# Then unset manifest properties prior to committing.
 	cat project.clj > ${tmp}/project.bak.2
 	setup-build-sig
 	sed -f ${tmp}/manifest.sed ${tmp}/project.bak.2 > project.clj
@@ -223,6 +237,7 @@ do
 		lein marg
 		lein install
 		
+		# Then unset manifest properties prior to committing.
 		cat project.clj > ${tmp}/project.bak.4
 		setup-build-sig
 		sed -f ${tmp}/manifest.sed ${tmp}/project.bak.4 > project.clj
@@ -235,15 +250,7 @@ do
 		fi
 	fi
 
-	# Finally, if we're in the UI project, build the uberwar - and should 
-	# probably deploy it to local Tomcat for test
-	if [ "${dir}" = "mw-ui" ]
-	then
-    	lein ring uberwar
-		sudo cp target/microworld.war /var/lib/tomcat7/webapps
-		echo "Deployed new WAR file to local Tomcat"
-	fi
-
+	# if nothing broke so far, clean up...
 	# rm -rf "${tmp}"
 	popd
 done
diff --git a/project.clj b/project.clj
index e5d5315..8c2ae67 100644
--- a/project.clj
+++ b/project.clj
@@ -1,13 +1,12 @@
-(defproject mw-engine "0.1.3-SNAPSHOT"
+(defproject mw-engine "0.1.2-SNAPSHOT"
   :description "Cellular automaton world builder."
   :url "http://www.journeyman.cc/microworld/"
   :manifest {
-             ;; do not reformat this! It is important for the buildall script
-             ;; that each of these properties is on a line with nothing else.
-		"build-signature-version" "0.1.3-SNAPSHOT"
-		"build-signature-user" "Simon Brooke"
-		"build-signature-email" "simon@journeyman.cc"
-		"build-signature-timestamp" "2014-07-27 11:54:52+01:00"
+             "build-signature-version" "unset"
+             "build-signature-user" "unset"
+             "build-signature-email" "unset"
+             "build-signature-timestamp" "unset"
+             "Implementation-Version" "unset"
              }
 
   :license {:name "GNU General Public License v2"
diff --git a/src/mw_engine/core.clj b/src/mw_engine/core.clj
index af5d686..ae3a065 100644
--- a/src/mw_engine/core.clj
+++ b/src/mw_engine/core.clj
@@ -2,8 +2,7 @@
 
 (ns mw-engine.core
   (:use mw-engine.utils)
-  (:require [mw-engine.world :as world]
-            ))
+  (:require [mw-engine.world :as world]))
 
 ;; Every rule is a function of two arguments, a cell and a world. If the rule
 ;; fires, it returns a new cell, which should have the same values for :x and
diff --git a/src/mw_engine/utils.clj b/src/mw_engine/utils.clj
index 10220b5..a63422d 100644
--- a/src/mw_engine/utils.clj
+++ b/src/mw_engine/utils.clj
@@ -164,3 +164,5 @@
             (map #(set-cell-property % x y property value)
                  row)))
         world))))
+
+
diff --git a/src/mw_engine/version.clj b/src/mw_engine/version.clj
new file mode 100644
index 0000000..18b9b0e
--- /dev/null
+++ b/src/mw_engine/version.clj
@@ -0,0 +1,11 @@
+(ns mw-engine.version
+  (:gen-class))
+
+(defn get-implementation-version 
+  "Get the implementation version from the package of this namespace, which must
+   be compiled into a class (see clojure.java.interop)"
+  [namespace-class]
+  (.getImplementationVersion (.getPackage namespace-class)))
+
+(defn -main []
+  (get-implementation-version (eval 'mw-engine.version)))