diff --git a/builtin/providers/azurerm/resource_arm_subnet.go b/builtin/providers/azurerm/resource_arm_subnet.go
index 796202c3e186..dbdb11f112de 100644
--- a/builtin/providers/azurerm/resource_arm_subnet.go
+++ b/builtin/providers/azurerm/resource_arm_subnet.go
@@ -151,6 +151,12 @@ func resourceArmSubnetRead(d *schema.ResourceData, meta interface{}) error {
 		}
 	}
 
+  if resp.Properties.RouteTable == nil {
+    d.Set("route_table_id", nil)
+  } else {
+    d.Set("route_table_id", *resp.Properties.RouteTable.ID)
+  }
+
 	return nil
 }