diff --git a/src/com/sheepit/client/Client.java b/src/com/sheepit/client/Client.java
index 24a6bb2..155eeb7 100644
--- a/src/com/sheepit/client/Client.java
+++ b/src/com/sheepit/client/Client.java
@@ -436,7 +436,7 @@ public class Client {
 			// no exception should be raised to actual launcher (applet or standalone)
 		}
 		
-		if (error != null && error == Error.Type.RENDERER_CRASHED) {
+		if (error != null && (error == Error.Type.RENDERER_CRASHED || error == Error.Type.RENDERER_KILLED_BY_USER)) {
 			// do nothing, we can ask for a job right away
 		}
 		else {
diff --git a/src/com/sheepit/client/Error.java b/src/com/sheepit/client/Error.java
index 65407db..ff963f4 100644
--- a/src/com/sheepit/client/Error.java
+++ b/src/com/sheepit/client/Error.java
@@ -38,6 +38,7 @@ public class Error {
 		RENDERER_CRASHED(12),
 		RENDERER_OUT_OF_VIDEO_MEMORY(13),
 		RENDERER_KILLED(14),
+		RENDERER_KILLED_BY_USER(20),
 		RENDERER_MISSING_LIBRARIES(15),
 		FAILED_TO_EXECUTE(16),
 		OS_NOT_SUPPORTED(17),
@@ -152,6 +153,8 @@ public class Error {
 				return "Failed to launch renderer. Please check if you have necessary libraries installed and if you have enough free space in your working directory.";
 			case RENDERER_KILLED:
 			    return "The renderer stopped because either you asked to stop or the server did (usually for a render time too high).";
+			case RENDERER_KILLED_BY_USER:
+				return "The renderer stopped because you've blocked its project.";
 			case SESSION_DISABLED:
 				return "The server has disabled your session. Your client may have generated a broken frame (GPU not compatible, not enough RAM/VRAM, etc).";
 			case RENDERER_NOT_AVAILABLE:
diff --git a/src/com/sheepit/client/Job.java b/src/com/sheepit/client/Job.java
index 8f69b1b..2f0d0b8 100644
--- a/src/com/sheepit/client/Job.java
+++ b/src/com/sheepit/client/Job.java
@@ -60,6 +60,7 @@ public class Job {
 	private boolean synchronousUpload;
 	private RenderProcess render;
 	private boolean askForRendererKill;
+	private boolean userBlockJob;
 	private Gui gui;
 	private Configuration config;
 	private Log log;
@@ -81,6 +82,7 @@ public class Job {
 		script = script_;
 		updateRenderingStatusMethod = update_method_;
 		askForRendererKill = false;
+		userBlockJob = false;
 		log = log_;
 		render = new RenderProcess();
 	}
@@ -133,6 +135,14 @@ public class Job {
 		return askForRendererKill;
 	}
 	
+	public void setUserBlockJob(boolean val) {
+		userBlockJob = val;
+	}
+	
+	public boolean getUserBlockJob() {
+		return userBlockJob;
+	}
+	
 	public String getRenderCommand() {
 		return rendererCommand;
 	}
@@ -328,6 +338,9 @@ public class Job {
 			
 			if (getAskForRendererKill()) {
 				log.debug("Client::runRenderer renderer didn't generate any frame but died due to a kill request");
+				if (getUserBlockJob()) {
+					return Error.Type.RENDERER_KILLED_BY_USER;
+				}
 				return Error.Type.RENDERER_KILLED;
 			}
 			
diff --git a/src/com/sheepit/client/standalone/swing/activity/Working.java b/src/com/sheepit/client/standalone/swing/activity/Working.java
index 3e9e9af..b355d61 100644
--- a/src/com/sheepit/client/standalone/swing/activity/Working.java
+++ b/src/com/sheepit/client/standalone/swing/activity/Working.java
@@ -16,6 +16,7 @@ import javax.swing.JButton;
 import javax.swing.JLabel;
 import com.sheepit.client.Client;
 import com.sheepit.client.Server;
+import com.sheepit.client.os.OS;
 import com.sheepit.client.standalone.GuiSwing;
 import com.sheepit.client.standalone.GuiSwing.ActivityType;
 
@@ -134,6 +135,12 @@ public class Working implements Activity {
 		parent.getContentPane().add(pauseButton, constraints);
 		
 		++currentRow;
+		JButton blockJob = new JButton("Block this project");
+		constraints.gridx = 1;
+		constraints.gridy = currentRow;
+		blockJob.addActionListener(new blockJobAction());
+		parent.getContentPane().add(blockJob, constraints);
+		
 		exitAfterFrame = new JButton("Exit after this frame");
 		constraints.gridx = 2;
 		constraints.gridy = currentRow;
@@ -238,4 +245,16 @@ public class Working implements Activity {
 		}
 	}
 	
+	class blockJobAction implements ActionListener {
+		@Override
+		public void actionPerformed(ActionEvent e) {
+			Client client = parent.getClient();
+			if (client != null) {
+				client.getRenderingJob().setAskForRendererKill(true);
+				client.getRenderingJob().setUserBlockJob(true);
+				OS.getOS().kill(client.getRenderingJob().getProcessRender().getProcess());
+			}
+		}
+	}
+	
 }