diff --git a/common/xrdp_constants.h b/common/xrdp_constants.h
index 2b229eae..fb5a0da7 100644
--- a/common/xrdp_constants.h
+++ b/common/xrdp_constants.h
@@ -201,6 +201,11 @@
 #define OSMINORTYPE_PSEUDO_XSERVER     0x0008
 #define OSMINORTYPE_WINDOWS_RT         0x0009
 
+/* Window List Capability Set: WndSupportLevel (MS-RDPERP 2.2.1.1.2) */
+#define TS_WINDOW_LEVEL_NOT_SUPPORTED  0x00000000
+#define TS_WINDOW_LEVEL_SUPPORTED      0x00000001
+#define TS_WINDOW_LEVEL_SUPPORTED_EX   0x00000002
+
 /* Extended Info Packet: performanceFlags (MS-RDPBCGR 2.2.1.11.1.1.1) */
 /* TODO: to be renamed */
 #define RDP5_DISABLE_NOTHING           0x00
diff --git a/libxrdp/xrdp_caps.c b/libxrdp/xrdp_caps.c
index d951d19a..2dc701b5 100644
--- a/libxrdp/xrdp_caps.c
+++ b/libxrdp/xrdp_caps.c
@@ -966,16 +966,17 @@ xrdp_caps_send_demand_active(struct xrdp_rdp *self)
     {
         /* Remote Programs Capability Set */
         caps_count++;
-        out_uint16_le(s, 0x0017); /* CAPSETTYPE_RAIL */
-        out_uint16_le(s, 8);
-        out_uint32_le(s, 3); /* TS_RAIL_LEVEL_SUPPORTED
-                              TS_RAIL_LEVEL_DOCKED_LANGBAR_SUPPORTED */
+        out_uint16_le(s, CAPSTYPE_RAIL);
+        out_uint16_le(s, 8); /* LengthCapability: MS-RDPERP 2.2.1.1.1 */
+        out_uint32_le(s, 3); /* See: https://msdn.microsoft.com/en-us/library/cc242518.aspx
+                                TS_RAIL_LEVEL_SUPPORTED
+                                TS_RAIL_LEVEL_DOCKED_LANGBAR_SUPPORTED */
 
         /* Window List Capability Set */
         caps_count++;
-        out_uint16_le(s, 0x0018); /* CAPSETTYPE_WINDOW */
-        out_uint16_le(s, 11);
-        out_uint32_le(s, 2); /* TS_WINDOW_LEVEL_SUPPORTED_EX */
+        out_uint16_le(s, CAPSTYPE_WINDOW);
+        out_uint16_le(s, 11); /* LengthCapability: MS-RDPERP 2.2.1.1.2 */
+        out_uint32_le(s, TS_WINDOW_LEVEL_SUPPORTED_EX);
         out_uint8(s, 3); /* NumIconCaches */
         out_uint16_le(s, 12); /* NumIconCacheEntries */
     }