diff --git a/mango/orders.py b/mango/orders.py
index c1565d2..b8037a4 100644
--- a/mango/orders.py
+++ b/mango/orders.py
@@ -66,6 +66,7 @@ class OrderType(enum.Enum):
     LIMIT = "LIMIT"
     IOC = "IOC"
     POST_ONLY = "POST_ONLY"
+    POST_ONLY_SLIDE = "POST_ONLY_SLIDE"
 
     @staticmethod
     def from_value(value: Decimal) -> "OrderType":
@@ -83,6 +84,9 @@ class OrderType(enum.Enum):
             return pyserum.enums.OrderType.IOC
         elif self == OrderType.POST_ONLY:
             return pyserum.enums.OrderType.POST_ONLY
+        elif self == OrderType.POST_ONLY_SLIDE:
+            # Best we can do in this situation
+            return pyserum.enums.OrderType.POST_ONLY
         else:
             return pyserum.enums.OrderType.LIMIT