diff --git a/cJSON.c b/cJSON.c
index cac1164b..27402d1f 100644
--- a/cJSON.c
+++ b/cJSON.c
@@ -403,6 +403,8 @@ CJSON_PUBLIC(double) cJSON_SetNumberHelper(cJSON *object, double number)
 CJSON_PUBLIC(char*) cJSON_SetValuestring(cJSON *object, const char *valuestring)
 {
     char *copy = NULL;
+    size_t v1_len;
+    size_t v2_len;
     /* if object's type is not cJSON_String or is cJSON_IsReference, it should not set valuestring */
     if ((object == NULL) || !(object->type & cJSON_String) || (object->type & cJSON_IsReference))
     {
@@ -413,8 +415,17 @@ CJSON_PUBLIC(char*) cJSON_SetValuestring(cJSON *object, const char *valuestring)
     {
         return NULL;
     }
-    if (strlen(valuestring) <= strlen(object->valuestring))
+
+    v1_len = strlen(valuestring);
+    v2_len = strlen(object->valuestring);
+
+    if (v1_len <= v2_len)
     {
+        /* strcpy does not handle overlapping string: [X1, X2] [Y1, Y2] => X2 < Y1 or Y2 < X1 */
+        if (!( valuestring + v1_len < object->valuestring || object->valuestring + v2_len < valuestring ))
+        {
+            return NULL;
+        }
         strcpy(object->valuestring, valuestring);
         return object->valuestring;
     }
diff --git a/tests/misc_tests.c b/tests/misc_tests.c
index ba3e003e..c558ac0d 100644
--- a/tests/misc_tests.c
+++ b/tests/misc_tests.c
@@ -456,6 +456,24 @@ static void cjson_functions_should_not_crash_with_null_pointers(void)
     cJSON_Delete(item);
 }
 
+static void cjson_set_valuestring_should_return_null_if_strings_overlap(void)
+{       
+    cJSON *obj;
+    char* str;
+    char* str2;
+
+    obj =  cJSON_Parse("\"foo0z\"");
+    
+    str =  cJSON_SetValuestring(obj, "abcde");
+    str += 1;
+    /* The string passed to strcpy overlap which is not allowed.*/
+    str2 = cJSON_SetValuestring(obj, str);
+    /* If it overlaps, the string will be messed up.*/
+    TEST_ASSERT_TRUE(strcmp(str, "bcde") == 0);
+    TEST_ASSERT_NULL(str2);
+    cJSON_Delete(obj);
+}
+
 static void *CJSON_CDECL failing_realloc(void *pointer, size_t size)
 {
     (void)size;
@@ -749,6 +767,7 @@ int CJSON_CDECL main(void)
     RUN_TEST(cjson_replace_item_via_pointer_should_replace_items);
     RUN_TEST(cjson_replace_item_in_object_should_preserve_name);
     RUN_TEST(cjson_functions_should_not_crash_with_null_pointers);
+    RUN_TEST(cjson_set_valuestring_should_return_null_if_strings_overlap);
     RUN_TEST(ensure_should_fail_on_failed_realloc);
     RUN_TEST(skip_utf8_bom_should_skip_bom);
     RUN_TEST(skip_utf8_bom_should_not_skip_bom_if_not_at_beginning);