diff --git a/src/com/sheepit/client/Client.java b/src/com/sheepit/client/Client.java
index fd180d6..08a164e 100644
--- a/src/com/sheepit/client/Client.java
+++ b/src/com/sheepit/client/Client.java
@@ -622,8 +622,9 @@ public class Client {
 	
 	protected Error.Type confirmJob(Job ajob) {
 		String extras_config = "";
-		if (this.config.getNbCores() > 0) {
-			extras_config = "&cores=" + this.config.getNbCores();
+		RenderProcess process = ajob.getProcessRender();
+		if (process != null && process.getCoresUsed() > 0) {
+			extras_config = "&cores=" + process.getCoresUsed();
 		}
 		
 		String url_real = String.format("%s?job=%s&frame=%s&rendertime=%d&revision=%s&memoryused=%s&extras=%s%s", this.server.getPage("validate-job"), ajob.getId(), ajob.getFrameNumber(), ajob.getProcessRender().getDuration(), ajob.getRevision(), ajob.getProcessRender().getMemoryUsed(), ajob.getExtras(), extras_config);
diff --git a/src/com/sheepit/client/Job.java b/src/com/sheepit/client/Job.java
index f9f209b..3686fb4 100644
--- a/src/com/sheepit/client/Job.java
+++ b/src/com/sheepit/client/Job.java
@@ -263,6 +263,7 @@ public class Job {
 			String line;
 			log.debug(command.toString());
 			OS os = OS.getOS();
+			process.setCoresUsed(config.getNbCores());
 			process.start();
 			getProcessRender().setProcess(os.exec(command, new_env));
 			BufferedReader input = new BufferedReader(new InputStreamReader(getProcessRender().getProcess().getInputStream()));
diff --git a/src/com/sheepit/client/RenderProcess.java b/src/com/sheepit/client/RenderProcess.java
index 0932d4a..108ea84 100644
--- a/src/com/sheepit/client/RenderProcess.java
+++ b/src/com/sheepit/client/RenderProcess.java
@@ -26,6 +26,7 @@ public class RenderProcess {
 	private long end;
 	private int remainingDuration;
 	private long memoryUsed; // in kB
+	private int coresUsed;
 	private Process process;
 	
 	public RenderProcess() {
@@ -33,6 +34,7 @@ public class RenderProcess {
 		start = -1;
 		end = -1;
 		memoryUsed = 0;
+		coresUsed = 0;
 		remainingDuration = 0;
 	}
 	
@@ -44,6 +46,14 @@ public class RenderProcess {
 		return memoryUsed;
 	}
 	
+	public void setCoresUsed(int val) {
+		coresUsed = val;
+	}
+	
+	public int getCoresUsed() {
+		return coresUsed;
+	}
+	
 	public long getStartTime() {
 		return start;
 	}