diff --git a/compose/config/schema.json b/compose/config/schema.json
index b615aa201..073a0da65 100644
--- a/compose/config/schema.json
+++ b/compose/config/schema.json
@@ -68,8 +68,18 @@
         },
 
         "mac_address": {"type": "string"},
-        "mem_limit": {"type": "number"},
-        "memswap_limit": {"type": "number"},
+        "mem_limit": {
+          "oneOf": [
+            {"type": "number"},
+            {"type": "string"}
+          ]
+        },
+        "memswap_limit": {
+          "oneOf": [
+            {"type": "number"},
+            {"type": "string"}
+          ]
+        },
         "name": {"type": "string"},
         "net": {"type": "string"},
         "pid": {"type": "string"},
diff --git a/tests/unit/config_test.py b/tests/unit/config_test.py
index c8a2d0db1..861d36bda 100644
--- a/tests/unit/config_test.py
+++ b/tests/unit/config_test.py
@@ -533,6 +533,16 @@ class MemoryOptionsTest(unittest.TestCase):
         )
         self.assertEqual(service_dict[0]['memswap_limit'], 2000000)
 
+    def test_memswap_can_be_a_string(self):
+        service_dict = config.load(
+            config.ConfigDetails(
+                {'foo': {'image': 'busybox', 'mem_limit': "1G", 'memswap_limit': "512M"}},
+                'tests/fixtures/extends',
+                'common.yml'
+            )
+        )
+        self.assertEqual(service_dict[0]['memswap_limit'], "512M")
+
 
 class EnvTest(unittest.TestCase):
     def test_parse_environment_as_list(self):