diff --git a/connect/transforms/src/main/java/org/apache/kafka/connect/transforms/Flatten.java b/connect/transforms/src/main/java/org/apache/kafka/connect/transforms/Flatten.java
index c5e4000..e9336a0 100644
--- a/connect/transforms/src/main/java/org/apache/kafka/connect/transforms/Flatten.java
+++ b/connect/transforms/src/main/java/org/apache/kafka/connect/transforms/Flatten.java
@@ -104,7 +104,7 @@
             Object value = entry.getValue();
             if (value == null) {
                 newRecord.put(fieldName(fieldNamePrefix, entry.getKey()), null);
-                return;
+                continue;
             }
 
             Schema.Type inferredType = ConnectSchema.schemaType(value.getClass());
diff --git a/connect/transforms/src/test/java/org/apache/kafka/connect/transforms/FlattenTest.java b/connect/transforms/src/test/java/org/apache/kafka/connect/transforms/FlattenTest.java
index d709054..9f9e5c8 100644
--- a/connect/transforms/src/test/java/org/apache/kafka/connect/transforms/FlattenTest.java
+++ b/connect/transforms/src/test/java/org/apache/kafka/connect/transforms/FlattenTest.java
@@ -254,4 +254,25 @@
         Schema transformedOptFieldSchema = SchemaBuilder.string().optional().defaultValue("child_default").build();
         assertEquals(transformedOptFieldSchema, transformedSchema.field("opt_field").schema());
     }
+    
+    @Test
+    public void testNullValueInStruct() {
+        xformKey.configure(Collections.<String, String>emptyMap());
+        
+        Map<String, String> aStructMap = new HashMap<>();
+        aStructMap.put("B", null);
+        aStructMap.put("C", "cValue");
+        aStructMap.put("D", "dValue");
+        
+        Map<String, Map<String, String>> key = Collections.singletonMap("A", aStructMap);
+        SourceRecord src = new SourceRecord(null, null, "topic", null, key, null, null);
+        SourceRecord transformed = xformKey.apply(src);
+
+        assertNull(transformed.keySchema());
+        assertTrue(transformed.key() instanceof Map);
+        Map<String, Object> transformedMap = (Map<String, Object>) transformed.key();
+        assertEquals(null, transformedMap.get("A.B"));
+        assertEquals(aStructMap.get("C"), transformedMap.get("A.C"));
+        assertEquals(aStructMap.get("D"), transformedMap.get("A.D"));
+    }
 }