diff --git a/utils/misc/src/main/java/org/onlab/packet/dhcp/Dhcp6ClientIdOption.java b/utils/misc/src/main/java/org/onlab/packet/dhcp/Dhcp6ClientIdOption.java
index 5623e71..f4f3fc8 100644
--- a/utils/misc/src/main/java/org/onlab/packet/dhcp/Dhcp6ClientIdOption.java
+++ b/utils/misc/src/main/java/org/onlab/packet/dhcp/Dhcp6ClientIdOption.java
@@ -49,7 +49,7 @@
             Dhcp6Duid duid = Dhcp6Duid.deserializer().deserialize(data, 0, data.length);
             this.setDuid(duid);
         } catch (DeserializationException e) {
-            throw new RuntimeException("Invalid DUID");
+            throw new IllegalArgumentException("Invalid DUID");
         }
 
     }
diff --git a/utils/misc/src/main/java/org/onlab/packet/dhcp/Dhcp6Duid.java b/utils/misc/src/main/java/org/onlab/packet/dhcp/Dhcp6Duid.java
index c8ca3bd..80675e2 100644
--- a/utils/misc/src/main/java/org/onlab/packet/dhcp/Dhcp6Duid.java
+++ b/utils/misc/src/main/java/org/onlab/packet/dhcp/Dhcp6Duid.java
@@ -51,7 +51,7 @@
                 case 3:
                     return DUID_LL;
                 default:
-                    throw new RuntimeException("Unknown type: " + type);
+                    throw new IllegalArgumentException("Unknown type: " + type);
             }
         }
     }
@@ -139,7 +139,7 @@
                 byteBuffer.put(linkLayerAddress);
                 break;
             default:
-                throw new RuntimeException("Unknown duidType: " + duidType.toString());
+                throw new IllegalArgumentException("Unknown duidType: " + duidType.toString());
         }
         return byteBuffer.array();
     }
@@ -171,7 +171,7 @@
                     byteBuffer.get(duid.linkLayerAddress);
                     break;
                 default:
-                    throw new RuntimeException("Unknown type: " + duidType);
+                    throw new IllegalArgumentException("Unknown type: " + duidType);
             }
             return duid;
         };
diff --git a/utils/misc/src/main/java/org/onlab/packet/dhcp/Dhcp6Option.java b/utils/misc/src/main/java/org/onlab/packet/dhcp/Dhcp6Option.java
index f19f735..8202b30 100644
--- a/utils/misc/src/main/java/org/onlab/packet/dhcp/Dhcp6Option.java
+++ b/utils/misc/src/main/java/org/onlab/packet/dhcp/Dhcp6Option.java
@@ -74,7 +74,7 @@
         try {
             this.payload = Data.deserializer().deserialize(data, 0, data.length);
         } catch (DeserializationException e) {
-            throw new RuntimeException("Invalid data");
+            throw new IllegalArgumentException("Invalid data");
         }
     }
 
diff --git a/utils/misc/src/main/java/org/onlab/util/Tools.java b/utils/misc/src/main/java/org/onlab/util/Tools.java
index bf9bea0..4b2cac9 100644
--- a/utils/misc/src/main/java/org/onlab/util/Tools.java
+++ b/utils/misc/src/main/java/org/onlab/util/Tools.java
@@ -388,7 +388,7 @@
         try {
             Thread.sleep(ms);
         } catch (InterruptedException e) {
-            throw new RuntimeException("Interrupted", e);
+            throw new IllegalStateException("Interrupted", e);
         }
     }
 
@@ -460,7 +460,7 @@
         try {
             Thread.sleep(random.nextInt(ms));
         } catch (InterruptedException e) {
-            throw new RuntimeException("Interrupted", e);
+            throw new IllegalStateException("Interrupted", e);
         }
     }
 
@@ -474,7 +474,7 @@
         try {
             Thread.sleep(ms, nanos);
         } catch (InterruptedException e) {
-            throw new RuntimeException("Interrupted", e);
+            throw new IllegalStateException("Interrupted", e);
         }
     }