diff --git a/src/main/java/org/apache/commons/collections4/list/TreeList.java b/src/main/java/org/apache/commons/collections4/list/TreeList.java
index 65ec38995f..9ab1ccd00d 100644
--- a/src/main/java/org/apache/commons/collections4/list/TreeList.java
+++ b/src/main/java/org/apache/commons/collections4/list/TreeList.java
@@ -686,7 +686,7 @@ private AVLNode<E> balance() {
                 }
                 return rotateLeft();
             default :
-                throw new RuntimeException("tree inconsistent!");
+                throw new IllegalStateException("tree inconsistent!");
             }
         }
 
diff --git a/src/main/java/org/apache/commons/collections4/sequence/SequencesComparator.java b/src/main/java/org/apache/commons/collections4/sequence/SequencesComparator.java
index acd6aa9849..327a7a5d62 100644
--- a/src/main/java/org/apache/commons/collections4/sequence/SequencesComparator.java
+++ b/src/main/java/org/apache/commons/collections4/sequence/SequencesComparator.java
@@ -234,7 +234,7 @@ private Snake getMiddleSnake(final int start1, final int end1, final int start2,
         }
 
         // this should not happen
-        throw new RuntimeException("Internal Error");
+        throw new IllegalStateException("Internal Error");
     }