diff --git a/spring-context/src/main/java/org/springframework/context/annotation/AdviceModeImportSelector.java b/spring-context/src/main/java/org/springframework/context/annotation/AdviceModeImportSelector.java
index 7da0201809..14f9f1bfa2 100644
--- a/spring-context/src/main/java/org/springframework/context/annotation/AdviceModeImportSelector.java
+++ b/spring-context/src/main/java/org/springframework/context/annotation/AdviceModeImportSelector.java
@@ -21,7 +21,6 @@ import java.lang.annotation.Annotation;
 import org.springframework.core.GenericTypeResolver;
 import org.springframework.core.annotation.AnnotationAttributes;
 import org.springframework.core.type.AnnotationMetadata;
-import org.springframework.util.Assert;
 
  /**
  * Convenient base class for {@link ImportSelector} implementations that select imports
@@ -62,13 +61,17 @@ public abstract class AdviceModeImportSelector<A extends Annotation> implements
 	public final String[] selectImports(AnnotationMetadata importingClassMetadata) {
 		Class<?> annoType = GenericTypeResolver.resolveTypeArgument(getClass(), AdviceModeImportSelector.class);
 		AnnotationAttributes attributes = AnnotationConfigUtils.attributesFor(importingClassMetadata, annoType);
-		Assert.notNull(attributes, String.format(
+		if (attributes == null) {
+			throw new IllegalArgumentException(String.format(
 				"@%s is not present on importing class '%s' as expected",
 				annoType.getSimpleName(), importingClassMetadata.getClassName()));
+		}
 
 		AdviceMode adviceMode = attributes.getEnum(this.getAdviceModeAttributeName());
 		String[] imports = selectImports(adviceMode);
-		Assert.notNull(imports, String.format("Unknown AdviceMode: '%s'", adviceMode));
+		if (imports == null) {
+			throw new IllegalArgumentException(String.format("Unknown AdviceMode: '%s'", adviceMode));
+		}
 		return imports;
 	}
 
diff --git a/spring-core/src/main/java/org/springframework/core/annotation/AnnotationAttributes.java b/spring-core/src/main/java/org/springframework/core/annotation/AnnotationAttributes.java
index 090621d803..a8bf6c21f5 100644
--- a/spring-core/src/main/java/org/springframework/core/annotation/AnnotationAttributes.java
+++ b/spring-core/src/main/java/org/springframework/core/annotation/AnnotationAttributes.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -105,7 +105,9 @@ public class AnnotationAttributes extends LinkedHashMap<String, Object> {
 	private <T> T doGet(String attributeName, Class<T> expectedType) {
 		Assert.hasText(attributeName, "attributeName must not be null or empty");
 		Object value = get(attributeName);
-		Assert.notNull(value, String.format("Attribute '%s' not found", attributeName));
+		if (value == null) {
+			throw new IllegalArgumentException(String.format("Attribute '%s' not found", attributeName));
+		}
 		if (!expectedType.isInstance(value)) {
 			if (expectedType.isArray() && expectedType.getComponentType().isInstance(value)) {
 				Object arrayValue = Array.newInstance(expectedType.getComponentType(), 1);
@@ -114,8 +116,8 @@ public class AnnotationAttributes extends LinkedHashMap<String, Object> {
 			}
 			else {
 				throw new IllegalArgumentException(
-						String.format("Attribute '%s' is of type [%s], but [%s] was expected. Cause: ",
-						attributeName, value.getClass().getSimpleName(), expectedType.getSimpleName()));
+						String.format("Attribute '%s' is of type [%s], but [%s] was expected.",
+						attributeName, value.getClass().getName(), expectedType.getName()));
 			}
 		}
 		return (T) value;
diff --git a/spring-core/src/main/java/org/springframework/core/env/ReadOnlySystemAttributesMap.java b/spring-core/src/main/java/org/springframework/core/env/ReadOnlySystemAttributesMap.java
index b5826c51c7..9cca8afdfa 100644
--- a/spring-core/src/main/java/org/springframework/core/env/ReadOnlySystemAttributesMap.java
+++ b/spring-core/src/main/java/org/springframework/core/env/ReadOnlySystemAttributesMap.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,8 +21,6 @@ import java.util.Collections;
 import java.util.Map;
 import java.util.Set;
 
-import org.springframework.util.Assert;
-
 /**
  * Read-only {@code Map<String, String>} implementation that is backed by system
  * properties or environment variables.
@@ -50,8 +48,11 @@ abstract class ReadOnlySystemAttributesMap implements Map<String, String> {
 	 */
 	@Override
 	public String get(Object key) {
-		Assert.isInstanceOf(String.class, key,
-				String.format("Expected key [%s] to be of type String, got %s", key, key.getClass().getName()));
+		if (!(key instanceof String)) {
+			throw new IllegalArgumentException(
+					"Key of type [" + (key != null ? key.getClass().getName() : "null") +
+					"] must be an instance of java.lang.String.");
+		}
 		return this.getSystemAttribute((String) key);
 	}