diff --git a/vertx-oracle-client/src/main/java/io/vertx/oracleclient/impl/Helper.java b/vertx-oracle-client/src/main/java/io/vertx/oracleclient/impl/Helper.java
index d50a1c463..be607161e 100644
--- a/vertx-oracle-client/src/main/java/io/vertx/oracleclient/impl/Helper.java
+++ b/vertx-oracle-client/src/main/java/io/vertx/oracleclient/impl/Helper.java
@@ -167,26 +167,26 @@ public static Object convertSqlValue(Object value) throws SQLException {
     }
 
     if (value instanceof OracleJsonValue) {
-      return convertOracleJsonValue((OracleJsonValue) value);
+      return convertOracleJsonValue((OracleJsonValue) value, true);
     }
 
     // fallback to String
     return value.toString();
   }
 
-  private static Object convertOracleJsonValue(OracleJsonValue oracleJson) {
+  private static Object convertOracleJsonValue(OracleJsonValue oracleJson, boolean topLevel) {
     if (oracleJson instanceof OracleJsonObject) {
       OracleJsonObject obj = (OracleJsonObject) oracleJson;
       Map<String, Object> map = new LinkedHashMap<>(obj.size());
       for (Map.Entry<String, OracleJsonValue> entry : obj.entrySet()) {
-        map.put(entry.getKey(), convertOracleJsonValue(entry.getValue()));
+        map.put(entry.getKey(), convertOracleJsonValue(entry.getValue(), false));
       }
       return new JsonObject(map);
     } else if (oracleJson instanceof OracleJsonArray) {
       OracleJsonArray arr = (OracleJsonArray) oracleJson;
       List<Object> list = new ArrayList<>(arr.size());
       for (OracleJsonValue element : arr) {
-        list.add(convertOracleJsonValue(element));
+        list.add(convertOracleJsonValue(element, false));
       }
       return new JsonArray(list);
     } else if (oracleJson instanceof OracleJsonString) {
@@ -204,7 +204,7 @@ private static Object convertOracleJsonValue(OracleJsonValue oracleJson) {
         case FALSE:
           return Boolean.FALSE;
         case NULL:
-          return Tuple.JSON_NULL;
+          return topLevel ? Tuple.JSON_NULL : null;
         default:
           return null;
       }
diff --git a/vertx-oracle-client/src/test/java/tests/oracleclient/OracleJsonDataTypeTest.java b/vertx-oracle-client/src/test/java/tests/oracleclient/OracleJsonDataTypeTest.java
index a3eb8da5f..124da72e8 100644
--- a/vertx-oracle-client/src/test/java/tests/oracleclient/OracleJsonDataTypeTest.java
+++ b/vertx-oracle-client/src/test/java/tests/oracleclient/OracleJsonDataTypeTest.java
@@ -301,4 +301,31 @@ public void testInsertJsonBooleanWithSqlWorkaround(TestContext ctx) {
         ctx.assertEquals(Boolean.TRUE, rows.iterator().next().getJson(0));
       }));
   }
+
+  @Test
+  public void testDecodeNestedJsonNull(TestContext ctx) {
+    JsonObject expected = new JsonObject().put("key", (String) null);
+    pool.preparedQuery("INSERT INTO json_test (id, data) VALUES (?, ?)")
+      .execute(Tuple.of(50, expected))
+      .compose(v -> pool.preparedQuery("SELECT data FROM json_test WHERE id = ?").execute(Tuple.of(50)))
+      .onComplete(ctx.asyncAssertSuccess(rows -> {
+        ctx.assertEquals(1, rows.size());
+        Row row = rows.iterator().next();
+        JsonObject result = row.getJsonObject(0);
+        ctx.assertTrue(result.containsKey("key"));
+        ctx.assertNull(result.getValue("key"));
+      }));
+  }
+
+  @Test
+  public void testDecodeTopLevelJsonNull(TestContext ctx) {
+    pool.preparedQuery("INSERT INTO json_test (id, data) VALUES (?, ?)")
+      .execute(Tuple.of(51, Tuple.JSON_NULL))
+      .compose(v -> pool.preparedQuery("SELECT data FROM json_test WHERE id = ?").execute(Tuple.of(51)))
+      .onComplete(ctx.asyncAssertSuccess(rows -> {
+        ctx.assertEquals(1, rows.size());
+        Row row = rows.iterator().next();
+        ctx.assertEquals(Tuple.JSON_NULL, row.getJson(0));
+      }));
+  }
 }