diff --git a/js/format-c2m.js b/js/format-c2m.js
index 8cc58e9..68e3d90 100644
--- a/js/format-c2m.js
+++ b/js/format-c2m.js
@@ -89,8 +89,8 @@ const TILE_ENCODING = {
     0x18: ['walker', '#direction', '#next'],
     0x19: ['glider', '#direction', '#next'],
     0x1a: ['ice_block', '#direction', '#next'],
-    0x1b: ['thinwall_e', '#next'],
-    0x1c: ['thinwall_s', '#next'],
+    0x1b: ['thinwall_s', '#next'],
+    0x1c: ['thinwall_e', '#next'],
     0x1d: ['thinwall_se', '#next'],
     0x1e: 'gravel',
     0x1f: 'button_green',