diff --git a/src/fr/inria/moex/classapp/Classification.java b/src/fr/inria/moex/classapp/Classification.java
index c975000506209f9124be0986e413d24857bd38b9..1be93441ab3ca1b9530790097a07548f84093de7 100644
--- a/src/fr/inria/moex/classapp/Classification.java
+++ b/src/fr/inria/moex/classapp/Classification.java
@@ -382,7 +382,7 @@ public class Classification implements Iterable<Classification> {
     public double distance( Classification classif2 ) {
     	int nbClasses = 0;
     	int nbCommon = 0;
-		if ( this == classif2 ) return 1.;
+		if ( this == classif2 ) return 0.;
 		for ( Classification cl: this ) {
 			nbClasses++;
 			for ( Classification cl2: classif2 ) {
@@ -393,7 +393,7 @@ public class Classification implements Iterable<Classification> {
 			}
 		}
 		for ( Classification cl2: classif2 ) nbClasses++;
-    	return (double)(2*nbCommon)/(double)nbClasses;
+    	return (double)(nbClasses-2*nbCommon)/(double)nbClasses;
     }
 	
 	public int nbForks() {