diff --git a/src/main/java/spoon/ContractVerifier.java b/src/main/java/spoon/ContractVerifier.java
index 5a975d9e2e2..7c4682f11bb 100644
--- a/src/main/java/spoon/ContractVerifier.java
+++ b/src/main/java/spoon/ContractVerifier.java
@@ -564,12 +564,12 @@ public void scan(CtRole role, CtElement element) {
 						assertTrue("Element of type " + element.getClass().getName()
 										+ " not found in Collection value of attribute of role " + role.name()
 										+ " of parent type " + parent.getClass().getName(),
-								((Collection<CtElement>) attributeOfParent).stream().anyMatch(e -> e == element));
+								((Collection<?>) attributeOfParent).stream().anyMatch(e -> e == element));
 					} else if (attributeOfParent instanceof Map) {
 						assertTrue("Element of type " + element.getClass().getName()
 										+ " not found in Map#values of attribute of role " + role.name()
 										+ " of parent type " + parent.getClass().getName(),
-								((Map<String, ?>) attributeOfParent).values().stream().anyMatch(e -> e == element));
+								((Map<?, ?>) attributeOfParent).values().stream().anyMatch(e -> e == element));
 					} else {
 						fail("Attribute of Role " + role + " not checked");
 					}