diff --git a/README.md b/README.md
index d1d8c28..7d8f0d3 100644
--- a/README.md
+++ b/README.md
@@ -85,6 +85,7 @@ $ curl --url vmpooler.company.com/vm
 ```
 
 #### POST /vm
+
 Useful for batch operations; post JSON (see format below), get back VMs.
 
 ```
@@ -105,7 +106,8 @@ $ curl -d '{"debian-7-i386":"2","debian-7-x86_64":"1"}' --url vmpooler.company.c
 }
 ```
 
-#### POST /vm/<pool>
+#### POST /vm/&lt;pool&gt;
+
 Check-out a VM or VMs.
 
 ```
@@ -141,7 +143,20 @@ $ curl -d --url vmpooler.company.com/vm/debian-7-i386+debian-7-i386+debian-7-x86
 }
 ```
 
-#### DELETE /vm/<hostnamename>
+#### PUT /vm/&lt;hostname&gt;
+
+Modify a checked-out VM.
+
+```
+$ curl -X PUT -d '{"lifetime":"2"}' --url vmpooler.company.com/vm/fq6qlpjlsskycq6
+```
+```json
+{
+  "ok": true
+}
+```
+
+#### DELETE /vm/&lt;hostname&gt;
 
 Schedule a checked-out VM for deletion.
 
diff --git a/lib/vmpooler/api.rb b/lib/vmpooler/api.rb
index 9fbde20..dd1cfb7 100644
--- a/lib/vmpooler/api.rb
+++ b/lib/vmpooler/api.rb
@@ -305,6 +305,28 @@ module Vmpooler
 
           JSON.pretty_generate(result)
         end
+
+        put '/vm/:hostname/?' do
+          content_type :json
+
+          result = {}
+
+          result['ok'] = false
+
+          if $redis.exists('vmpooler__vm__'+params[:hostname])
+            jdata = JSON.parse(request.body.read)
+
+            jdata.each do |param, arg|
+              case param
+                when 'lifetime'
+                  $redis.hset('vmpooler__vm__'+params[:hostname], param, arg)
+                  result['ok'] = true
+              end
+            end
+          end
+
+          JSON.pretty_generate(result)
+        end
       }
 
       my_app.run!
diff --git a/lib/vmpooler/pool_manager.rb b/lib/vmpooler/pool_manager.rb
index 944c79e..cc50e1d 100644
--- a/lib/vmpooler/pool_manager.rb
+++ b/lib/vmpooler/pool_manager.rb
@@ -380,9 +380,11 @@ module Vmpooler
           $redis.smembers('vmpooler__running__'+pool['name']).each do |vm|
             if ($redis.hget('vmpooler__active__'+pool['name'], vm))
               running = (Time.now - Time.parse($redis.hget('vmpooler__active__'+pool['name'], vm)))/60/60
+              lifetime = $redis.hget('vmpooler__vm__'+vm, 'lifetime') || $config[:config]['vm_lifetime']
+
               if (
-                ($config[:config]['vm_lifetime'] > 0) and
-                (running > $config[:config]['vm_lifetime'])
+                (lifetime.to_i > 0) and
+                (running.to_i > lifetime.to_i)
               )
                 $redis.smove('vmpooler__running__'+pool['name'], 'vmpooler__completed__'+pool['name'], vm)