diff --git a/src/main/java/org/springframework/data/repository/core/support/AbstractRepositoryMetadata.java b/src/main/java/org/springframework/data/repository/core/support/AbstractRepositoryMetadata.java
index 18aaf8bc5..1db63e60f 100644
--- a/src/main/java/org/springframework/data/repository/core/support/AbstractRepositoryMetadata.java
+++ b/src/main/java/org/springframework/data/repository/core/support/AbstractRepositoryMetadata.java
@@ -59,7 +59,8 @@ public abstract class AbstractRepositoryMetadata implements RepositoryMetadata {
 		return Iterable.class.isAssignableFrom(rawType) ? returnTypeInfo.getComponentType().getType() : rawType;
 	}
 
-	/* (non-Javadoc)
+	/* 
+	 * (non-Javadoc)
 	 * @see org.springframework.data.repository.core.RepositoryMetadata#getRepositoryInterface()
 	 */
 	public Class<?> getRepositoryInterface() {
diff --git a/src/main/java/org/springframework/data/repository/core/support/AnnotationRepositoryMetadata.java b/src/main/java/org/springframework/data/repository/core/support/AnnotationRepositoryMetadata.java
index d68ddb37a..7539bc3c6 100644
--- a/src/main/java/org/springframework/data/repository/core/support/AnnotationRepositoryMetadata.java
+++ b/src/main/java/org/springframework/data/repository/core/support/AnnotationRepositoryMetadata.java
@@ -69,32 +69,24 @@ public class AnnotationRepositoryMetadata extends AbstractRepositoryMetadata {
 		return this.domainType;
 	}
 
-	/**
-	 * @param repositoryInterface must not be {@literal null}.
-	 * @return the resolved domain type, never {@literal null}.
-	 */
 	private Class<? extends Serializable> resolveIdType(Class<?> repositoryInterface) {
 
-		Assert.notNull(repositoryInterface, "Repository interface must not be null!");
-
 		RepositoryDefinition annotation = repositoryInterface.getAnnotation(RepositoryDefinition.class);
-		Assert.isTrue(annotation != null && annotation.idClass() != null,
-				String.format("Could not resolve id type of %s!", repositoryInterface));
+
+		if (annotation == null || annotation.idClass() == null) {
+			throw new IllegalArgumentException(String.format("Could not resolve id type of %s!", repositoryInterface));
+		}
 
 		return annotation.idClass();
 	}
 
-	/**
-	 * @param repositoryInterface must not be {@literal null}.
-	 * @return the resolved domain type, never {@literal null}.
-	 */
 	private Class<?> resolveDomainType(Class<?> repositoryInterface) {
 
-		Assert.notNull(repositoryInterface, "Repository interface must not be null!");
-
 		RepositoryDefinition annotation = repositoryInterface.getAnnotation(RepositoryDefinition.class);
-		Assert.isTrue(annotation != null && annotation.domainClass() != null,
-				String.format("Could not resolve domain type of %s!", repositoryInterface));
+
+		if (annotation == null || annotation.domainClass() == null) {
+			throw new IllegalArgumentException(String.format("Could not resolve domain type of %s!", repositoryInterface));
+		}
 
 		return annotation.domainClass();
 	}
diff --git a/src/main/java/org/springframework/data/repository/core/support/DefaultRepositoryMetadata.java b/src/main/java/org/springframework/data/repository/core/support/DefaultRepositoryMetadata.java
index 7aff93972..d6db24293 100644
--- a/src/main/java/org/springframework/data/repository/core/support/DefaultRepositoryMetadata.java
+++ b/src/main/java/org/springframework/data/repository/core/support/DefaultRepositoryMetadata.java
@@ -41,7 +41,7 @@ public class DefaultRepositoryMetadata extends AbstractRepositoryMetadata {
 	/**
 	 * Creates a new {@link DefaultRepositoryMetadata} for the given repository interface.
 	 * 
-	 * @param repositoryInterface
+	 * @param repositoryInterface must not be {@literal null}.
 	 */
 	public DefaultRepositoryMetadata(Class<?> repositoryInterface) {
 
@@ -70,33 +70,26 @@ public class DefaultRepositoryMetadata extends AbstractRepositoryMetadata {
 		return this.idType;
 	}
 
-	/**
-	 * @param repositoryInterface must not be {@literal null}.
-	 * @return the resolved domain type, never {@literal null}.
-	 */
-	private Class<?> resolveDomainType(Class<?> repositoryInterface) {
-
-		Assert.notNull(repositoryInterface, "Repository interface must not be null!");
+	@SuppressWarnings("unchecked")
+	private Class<? extends Serializable> resolveIdType(Class<?> repositoryInterface) {
 
 		Class<?>[] arguments = resolveTypeArguments(repositoryInterface, Repository.class);
-		Assert.isTrue(arguments != null && arguments[0] != null,
-				String.format("Could not resolve domain type of %s!", repositoryInterface));
 
-		return arguments[0];
-	}
+		if (arguments == null || arguments[1] == null) {
+			throw new IllegalArgumentException(String.format("Could not resolve id type of %s!", repositoryInterface));
+		}
 
-	/**
-	 * @param repositoryInterface must not be {@literal null}.
-	 * @return the resolved id type, never {@literal null}.
-	 */
-	private Class<? extends Serializable> resolveIdType(Class<?> repositoryInterface) {
+		return (Class<? extends Serializable>) arguments[1];
+	}
 
-		Assert.notNull(repositoryInterface, "Repository interface must not be null!");
+	private Class<?> resolveDomainType(Class<?> repositoryInterface) {
 
 		Class<?>[] arguments = resolveTypeArguments(repositoryInterface, Repository.class);
-		Assert.isTrue(arguments != null && arguments[1] != null,
-				String.format("Could not resolve id type of %s!", repositoryInterface));
 
-		return (Class<? extends Serializable>) arguments[1];
+		if (arguments == null || arguments[0] == null) {
+			throw new IllegalArgumentException(String.format("Could not resolve domain type of %s!", repositoryInterface));
+		}
+
+		return arguments[0];
 	}
 }
diff --git a/src/test/java/org/springframework/data/repository/core/support/DefaultRepositoryMetadataUnitTests.java b/src/test/java/org/springframework/data/repository/core/support/DefaultRepositoryMetadataUnitTests.java
index ba03d5cb3..c4a2fabc8 100644
--- a/src/test/java/org/springframework/data/repository/core/support/DefaultRepositoryMetadataUnitTests.java
+++ b/src/test/java/org/springframework/data/repository/core/support/DefaultRepositoryMetadataUnitTests.java
@@ -88,7 +88,6 @@ public class DefaultRepositoryMetadataUnitTests {
 	public void looksUpIdClassCorrectly() throws Exception {
 
 		RepositoryMetadata metadata = new DefaultRepositoryMetadata(UserRepository.class);
-
 		assertEquals(Integer.class, metadata.getIdType());
 	}