diff --git a/pom.xml b/pom.xml
index 5fe51bd099..d5ce7e7619 100644
--- a/pom.xml
+++ b/pom.xml
@@ -5,7 +5,7 @@
 
 	<groupId>org.springframework.data</groupId>
 	<artifactId>spring-data-mongodb-parent</artifactId>
-	<version>3.2.0-SNAPSHOT</version>
+	<version>3.2.0-GH-3623-SNAPSHOT</version>
 	<packaging>pom</packaging>
 
 	<name>Spring Data MongoDB</name>
diff --git a/spring-data-mongodb-benchmarks/pom.xml b/spring-data-mongodb-benchmarks/pom.xml
index f0fbb601c8..f25c5b5837 100644
--- a/spring-data-mongodb-benchmarks/pom.xml
+++ b/spring-data-mongodb-benchmarks/pom.xml
@@ -7,7 +7,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>3.2.0-SNAPSHOT</version>
+		<version>3.2.0-GH-3623-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 
diff --git a/spring-data-mongodb-distribution/pom.xml b/spring-data-mongodb-distribution/pom.xml
index 1a17321782..755e7476d9 100644
--- a/spring-data-mongodb-distribution/pom.xml
+++ b/spring-data-mongodb-distribution/pom.xml
@@ -14,7 +14,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>3.2.0-SNAPSHOT</version>
+		<version>3.2.0-GH-3623-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 
diff --git a/spring-data-mongodb/pom.xml b/spring-data-mongodb/pom.xml
index 0248517caf..e490be9ba8 100644
--- a/spring-data-mongodb/pom.xml
+++ b/spring-data-mongodb/pom.xml
@@ -11,7 +11,7 @@
 	<parent>
 		<groupId>org.springframework.data</groupId>
 		<artifactId>spring-data-mongodb-parent</artifactId>
-		<version>3.2.0-SNAPSHOT</version>
+		<version>3.2.0-GH-3623-SNAPSHOT</version>
 		<relativePath>../pom.xml</relativePath>
 	</parent>
 
diff --git a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/AggregationUtils.java b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/AggregationUtils.java
index 8a8ffa0542..6078f23a15 100644
--- a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/AggregationUtils.java
+++ b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/AggregationUtils.java
@@ -163,9 +163,9 @@ static void appendLimitAndOffsetIfPresent(List<AggregationOperation> aggregation
 	 * @throws IllegalArgumentException when none of the above rules is met.
 	 */
 	@Nullable
-	static <T> T extractSimpleTypeResult(Document source, Class<T> targetType, MongoConverter converter) {
+	static <T> T extractSimpleTypeResult(@Nullable Document source, Class<T> targetType, MongoConverter converter) {
 
-		if (source.isEmpty()) {
+		if (source == null || source.isEmpty()) {
 			return null;
 		}
 
diff --git a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/query/StringBasedAggregationUnitTests.java b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/query/StringBasedAggregationUnitTests.java
index 59656e3030..00506229ea 100644
--- a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/query/StringBasedAggregationUnitTests.java
+++ b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/query/StringBasedAggregationUnitTests.java
@@ -159,6 +159,14 @@ public void returnCollection() {
 		assertThat(executeAggregation("returnCollection").result).isEqualTo(expected);
 	}
 
+	@Test // GH-3623
+	public void returnNullWhenSingleResultIsNotPresent() {
+
+		when(aggregationResults.getMappedResults()).thenReturn(Collections.emptyList());
+
+		assertThat(executeAggregation("simpleReturnType").result).isNull();
+	}
+
 	@Test // DATAMONGO-2153
 	public void returnRawResultType() {
 		assertThat(executeAggregation("returnRawResultType").result).isEqualTo(aggregationResults);
@@ -312,6 +320,9 @@ private interface SampleRepository extends Repository<Person, Long> {
 
 		@Aggregation(RAW_GROUP_BY_LASTNAME_STRING)
 		Page<Person> invalidPageReturnType(Pageable page);
+
+		@Aggregation(RAW_GROUP_BY_LASTNAME_STRING)
+		String simpleReturnType();
 	}
 
 	static class PersonAggregate {