diff --git a/iidm/iidm-groovy-extension/src/main/groovy/eu/itesla_project/iidm/network/IdentifiableExtension.groovy b/iidm/iidm-groovy-extension/src/main/groovy/eu/itesla_project/iidm/network/IdentifiableExtension.groovy
index f38ea4a6..545ca808 100644
--- a/iidm/iidm-groovy-extension/src/main/groovy/eu/itesla_project/iidm/network/IdentifiableExtension.groovy
+++ b/iidm/iidm-groovy-extension/src/main/groovy/eu/itesla_project/iidm/network/IdentifiableExtension.groovy
@@ -14,15 +14,7 @@ class IdentifiableExtension {
     static Object propertyMissing(Identifiable self, String name) {
         // first check if an extension exist then a property
         Identifiable.Extension extension = self.getExtensionByName(name)
-        if (extension != null) {
-            extension
-        } else {
-            Object value = self.properties[name]
-            if (value == null) {
-                throw new RuntimeException("Property '" + name + "' of '" + self.id + "' not found")
-            }
-            value
-        }
+        extension != null ? extension : self.properties[name]
     }
 
     static void propertyMissing(Identifiable self, String name, Object value) {
diff --git a/iidm/iidm-groovy-extension/src/test/groovy/eu/itesla_project/iidm/network/IdentifiableExtensionTest.groovy b/iidm/iidm-groovy-extension/src/test/groovy/eu/itesla_project/iidm/network/IdentifiableExtensionTest.groovy
index f0903d28..edbe25d4 100644
--- a/iidm/iidm-groovy-extension/src/test/groovy/eu/itesla_project/iidm/network/IdentifiableExtensionTest.groovy
+++ b/iidm/iidm-groovy-extension/src/test/groovy/eu/itesla_project/iidm/network/IdentifiableExtensionTest.groovy
@@ -45,11 +45,7 @@ class IdentifiableExtensionTest {
     @Test
     void testProperty() {
         assertFalse(s.hasProperty())
-        try {
-            s.greeting
-            fail()
-        } catch (Exception ignored) {
-        }
+        assertNull(s.greeting)
         s.greeting = "hello"
         assertEquals("hello", s.getProperties().getProperty("greeting"))
         assertEquals("hello", s.greeting)
@@ -57,11 +53,7 @@ class IdentifiableExtensionTest {
 
     @Test
     void testExtension() {
-        try {
-            s.foo
-            fail()
-        } catch (Exception ignored) {
-        }
+        assertNull(s.foo)
         s.addExtension(Substation.class, new Foo())
         assertNotNull(s.foo)
         s.foo.value = 3f