diff --git a/src/main/java/org/apache/commons/lang3/Validate.java b/src/main/java/org/apache/commons/lang3/Validate.java
index be26aa70e..c0e37d7b0 100644
--- a/src/main/java/org/apache/commons/lang3/Validate.java
+++ b/src/main/java/org/apache/commons/lang3/Validate.java
@@ -1163,8 +1163,7 @@ public class Validate {
     public static void isInstanceOf(final Class<?> type, final Object obj) {
         // TODO when breaking BC, consider returning obj
         if (!type.isInstance(obj)) {
-            throw new IllegalArgumentException(String.format(DEFAULT_IS_INSTANCE_OF_EX_MESSAGE, type.getName(),
-                    obj == null ? "null" : obj.getClass().getName()));
+            throw new IllegalArgumentException(String.format(DEFAULT_IS_INSTANCE_OF_EX_MESSAGE, type.getName(), ClassUtils.getName(obj, "null")));
         }
     }
 
diff --git a/src/main/java/org/apache/commons/lang3/time/FastDatePrinter.java b/src/main/java/org/apache/commons/lang3/time/FastDatePrinter.java
index 6ed587dae..d86b25e32 100644
--- a/src/main/java/org/apache/commons/lang3/time/FastDatePrinter.java
+++ b/src/main/java/org/apache/commons/lang3/time/FastDatePrinter.java
@@ -32,6 +32,7 @@ import java.util.TimeZone;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 
+import org.apache.commons.lang3.ClassUtils;
 import org.apache.commons.lang3.LocaleUtils;
 import org.apache.commons.lang3.exception.ExceptionUtils;
 
@@ -424,8 +425,7 @@ public class FastDatePrinter implements DatePrinter, Serializable {
         if (obj instanceof Long) {
             return format(((Long) obj).longValue(), toAppendTo);
         }
-        throw new IllegalArgumentException("Unknown class: " +
-            (obj == null ? "<null>" : obj.getClass().getName()));
+        throw new IllegalArgumentException("Unknown class: " + ClassUtils.getName(obj, "<null>"));
     }
 
     /**
@@ -445,8 +445,7 @@ public class FastDatePrinter implements DatePrinter, Serializable {
         if (obj instanceof Long) {
             return format(((Long) obj).longValue());
         }
-        throw new IllegalArgumentException("Unknown class: " +
-            (obj == null ? "<null>" : obj.getClass().getName()));
+        throw new IllegalArgumentException("Unknown class: " + ClassUtils.getName(obj, "<null>"));
     }
 
     /* (non-Javadoc)