diff --git a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryExecution.java b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryExecution.java
index d441938f0..77d718244 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryExecution.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryExecution.java
@@ -54,6 +54,7 @@ import org.springframework.util.ReflectionUtils;
  * @author Thomas Darimont
  * @author Mark Paluch
  * @author Nicolas Cirigliano
+ * @author Jens Schauder
  */
 public abstract class JpaQueryExecution {
 
@@ -221,13 +222,14 @@ public abstract class JpaQueryExecution {
 
 		/**
 		 * Creates an execution that automatically flushes the given {@link EntityManager} before execution and/or
-		 * clears the given {@link EntityManager} after execution if the given {@link EntityManager} is not
-		 * {@literal null}.
+		 * clears the given {@link EntityManager} after execution.
 		 * 
-		 * @param em
+		 * @param em Must not be {@literal null}.
 		 */
 		public ModifyingExecution(JpaQueryMethod method, EntityManager em) {
 
+			Assert.notNull(em, "The EntityManager must not be null.");
+
 			Class<?> returnType = method.getReturnType();
 
 			boolean isVoid = void.class.equals(returnType) || Void.class.equals(returnType);
@@ -243,13 +245,13 @@ public abstract class JpaQueryExecution {
 		@Override
 		protected Object doExecute(AbstractJpaQuery query, Object[] values) {
 
-			if (em != null && flush) {
+			if (flush) {
 				em.flush();
 			}
 
 			int result = query.createQuery(values).executeUpdate();
 
-			if (em != null && clear) {
+			if (clear) {
 				em.clear();
 			}
 
diff --git a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryMethod.java b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryMethod.java
index b1915c38a..6f2408f3a 100644
--- a/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryMethod.java
+++ b/src/main/java/org/springframework/data/jpa/repository/query/JpaQueryMethod.java
@@ -287,7 +287,7 @@ public class JpaQueryMethod extends QueryMethod {
 	/**
 	 * Returns whether we should flush automatically for modifying queries.
 	 * 
-	 * @return
+	 * @return whether we should flush automatically.
 	 */
 	boolean getFlushAutomatically() {
 		return getMergedOrDefaultAnnotationValue("flushAutomatically", Modifying.class, Boolean.class);
@@ -296,7 +296,7 @@ public class JpaQueryMethod extends QueryMethod {
 	/**
 	 * Returns whether we should clear automatically for modifying queries.
 	 *
-	 * @return
+	 * @return whether we should clear automatically.
 	 */
 	boolean getClearAutomatically() {
 		return getMergedOrDefaultAnnotationValue("clearAutomatically", Modifying.class, Boolean.class);
diff --git a/src/test/java/org/springframework/data/jpa/repository/query/JpaQueryExecutionUnitTests.java b/src/test/java/org/springframework/data/jpa/repository/query/JpaQueryExecutionUnitTests.java
index 683602f03..958fb9353 100644
--- a/src/test/java/org/springframework/data/jpa/repository/query/JpaQueryExecutionUnitTests.java
+++ b/src/test/java/org/springframework/data/jpa/repository/query/JpaQueryExecutionUnitTests.java
@@ -28,6 +28,7 @@ import javax.persistence.EntityManager;
 import javax.persistence.Query;
 import javax.persistence.TypedQuery;
 
+import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.Mock;
@@ -47,6 +48,7 @@ import org.springframework.data.repository.query.Parameters;
  * @author Thomas Darimont
  * @author Mark Paluch
  * @author Nicolas Cirigliano
+ * @author Jens Schauder
  */
 @RunWith(MockitoJUnitRunner.class)
 public class JpaQueryExecutionUnitTests {
@@ -58,6 +60,14 @@ public class JpaQueryExecutionUnitTests {
 
 	@Mock TypedQuery<Long> countQuery;
 
+	@Before
+	public void setUp(){
+
+		when(query.executeUpdate()).thenReturn(0);
+		when(jpaQuery.createQuery(Mockito.any(Object[].class))).thenReturn(query);
+		when(jpaQuery.getQueryMethod()).thenReturn(method);
+	}
+
 	@Test(expected = IllegalArgumentException.class)
 	public void rejectsNullQuery() {
 
@@ -83,15 +93,12 @@ public class JpaQueryExecutionUnitTests {
 		}.execute(jpaQuery, new Object[] {}), is(nullValue()));
 	}
 
-	@Test
+	@Test // DATAJPA-806
 	@SuppressWarnings({ "unchecked", "rawtypes" })
 	public void modifyingExecutionFlushesEntityManagerIfSet() {
 
-		when(query.executeUpdate()).thenReturn(0);
 		when(method.getReturnType()).thenReturn((Class) void.class);
 		when(method.getFlushAutomatically()).thenReturn(true);
-		when(jpaQuery.createQuery(Mockito.any(Object[].class))).thenReturn(query);
-		when(jpaQuery.getQueryMethod()).thenReturn(method);
 
 		ModifyingExecution execution = new ModifyingExecution(method, em);
 		execution.execute(jpaQuery, new Object[] {});
@@ -104,11 +111,8 @@ public class JpaQueryExecutionUnitTests {
 	@SuppressWarnings({ "unchecked", "rawtypes" })
 	public void modifyingExecutionClearsEntityManagerIfSet() {
 
-		when(query.executeUpdate()).thenReturn(0);
 		when(method.getReturnType()).thenReturn((Class) void.class);
 		when(method.getClearAutomatically()).thenReturn(true);
-		when(jpaQuery.createQuery(Mockito.any(Object[].class))).thenReturn(query);
-		when(jpaQuery.getQueryMethod()).thenReturn(method);
 
 		ModifyingExecution execution = new ModifyingExecution(method, em);
 		execution.execute(jpaQuery, new Object[] {});