diff --git a/src/main/java/org/springframework/data/repository/query/ReturnedType.java b/src/main/java/org/springframework/data/repository/query/ReturnedType.java
index 8ff15d351..09dbadb96 100644
--- a/src/main/java/org/springframework/data/repository/query/ReturnedType.java
+++ b/src/main/java/org/springframework/data/repository/query/ReturnedType.java
@@ -191,7 +191,9 @@ public abstract class ReturnedType {
 			List<String> properties = new ArrayList<String>();
 
 			for (PropertyDescriptor descriptor : information.getInputProperties()) {
-				properties.add(descriptor.getName());
+				if (!properties.contains(descriptor.getName())) {
+					properties.add(descriptor.getName());
+				}
 			}
 
 			return properties;
diff --git a/src/test/java/org/springframework/data/repository/query/ReturnedTypeUnitTests.java b/src/test/java/org/springframework/data/repository/query/ReturnedTypeUnitTests.java
index f3d3cbaa2..384f24e83 100644
--- a/src/test/java/org/springframework/data/repository/query/ReturnedTypeUnitTests.java
+++ b/src/test/java/org/springframework/data/repository/query/ReturnedTypeUnitTests.java
@@ -179,6 +179,20 @@ public class ReturnedTypeUnitTests {
 		assertThat(type.isProjecting(), is(false));
 	}
 
+	/**
+	 * @see DATACMNS-963
+	 */
+	@Test
+	public void detectsDistinctInputProperties() {
+
+		ReturnedType type = ReturnedType.of(Child.class, Object.class, new SpelAwareProxyProjectionFactory());
+
+		List<String> properties = type.getInputProperties();
+
+		assertThat(properties, hasSize(1));
+		assertThat(properties, contains("firstname"));
+	}
+
 	private static ReturnedType getReturnedType(String methodName, Class<?>... parameters) throws Exception {
 		return getQueryMethod(methodName, parameters).getResultProcessor().getReturnedType();
 	}
@@ -262,4 +276,12 @@ public class ReturnedTypeUnitTests {
 		@Value("#{target.firstname + ' ' + target.lastname}")
 		String getFullName();
 	}
+
+	static interface Parent {
+		String getFirstname();
+	}
+
+	static interface Child extends Parent {
+		String getFirstname();
+	}
 }