diff --git a/src/main/java/org/codehaus/jettison/json/JSONObject.java b/src/main/java/org/codehaus/jettison/json/JSONObject.java
index 0c15d74..541cf72 100644
--- a/src/main/java/org/codehaus/jettison/json/JSONObject.java
+++ b/src/main/java/org/codehaus/jettison/json/JSONObject.java
@@ -268,7 +268,7 @@ public JSONObject(Map map) {
             if (v instanceof Collection) {
                 myHashMap.put(entry.getKey(), new JSONArray((Collection) v));
             }
-            if (v instanceof Map) {
+            if (v instanceof Map && v != map) {
                 myHashMap.put(entry.getKey(), new JSONObject((Map) v));
             }
         }
diff --git a/src/test/java/org/codehaus/jettison/json/JSONObjectTest.java b/src/test/java/org/codehaus/jettison/json/JSONObjectTest.java
index acd8246..1026cea 100644
--- a/src/test/java/org/codehaus/jettison/json/JSONObjectTest.java
+++ b/src/test/java/org/codehaus/jettison/json/JSONObjectTest.java
@@ -2,6 +2,11 @@
 
 import junit.framework.TestCase;
 
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
 public class JSONObjectTest extends TestCase {
     public void testEquals() throws Exception {
     	JSONObject aJsonObj = new JSONObject("{\"x\":\"y\"}");
@@ -148,4 +153,10 @@ public void testMalformedArray() throws Exception {
         }
     }
 
+    // https://github.com/jettison-json/jettison/issues/52
+    public void testIssue52() throws Exception {
+        Map<String,Object> map = new HashMap<>();
+        map.put("t",map);
+        new JSONObject(map);
+    }
 }