diff --git a/packages/concerto-analysis/src/compare-config.ts b/packages/concerto-analysis/src/compare-config.ts
index 511f660dc..25581c9c5 100644
--- a/packages/concerto-analysis/src/compare-config.ts
+++ b/packages/concerto-analysis/src/compare-config.ts
@@ -53,6 +53,8 @@ export const defaultCompareConfig: CompareConfig = {
         'optional-property-added': CompareResult.PATCH,
         'required-property-removed': CompareResult.MAJOR,
         'optional-property-removed': CompareResult.MAJOR,
+        'class-declaration-abstract-to-concrete': CompareResult.MINOR,
+        'class-declaration-concrete-to-abstract': CompareResult.MAJOR, 
         'namespace-changed': CompareResult.ERROR,
         'enum-value-added': CompareResult.PATCH,
         'enum-value-removed': CompareResult.MAJOR,
diff --git a/packages/concerto-analysis/src/comparers/class-declarations.ts b/packages/concerto-analysis/src/comparers/class-declarations.ts
index 9da52b59b..a00190a70 100644
--- a/packages/concerto-analysis/src/comparers/class-declarations.ts
+++ b/packages/concerto-analysis/src/comparers/class-declarations.ts
@@ -54,11 +54,25 @@ const classDeclarationTypeChanged: ComparerFactory = (context) => ({
         if (aType === bType) {
             return;
         }
-        context.report({
-            key: 'class-declaration-type-changed',
-            message: `The ${aType} "${a.getName()}" changed type from ${aType} to ${bType}`,
-            element: a
-        });
+        if(aType !== bType){
+            context.report({
+                key: `class-declaration-type-changed`,
+                message: `The ${aType} "${a.getName()}" changed from ${aType} to ${bType}`,
+                element: a
+            });
+        }
+  
+        //add Logic for abstractness changes
+        const isAbstract = (declaration) => declaration.isAbstract();
+        if (isAbstract(a) !== isAbstract(b)) {
+            const changeType = isAbstract(a) ? 'abstract to concrete' : 'concrete to abstract';
+            const changeKey =isAbstract(a) ? `class-declaration-abstract-to-concrete` : `class-declaration-concrete-to-abstract`;
+            context.report({
+                key: changeKey,
+                message: `The class "${a.getName()}" changed from ${changeType}.`,
+                element: a
+            });
+        }
     }
 });