diff --git a/src/util/directiontables.cpp b/src/util/directiontables.cpp
index d700355bc..b4d3eef23 100644
--- a/src/util/directiontables.cpp
+++ b/src/util/directiontables.cpp
@@ -110,7 +110,7 @@ const v3s16 g_27dirs[27] =
 	v3s16(0,0,0),
 };
 
-constexpr u8 wallmounted_to_facedir[6] = {
+constexpr const u8 wallmounted_to_facedir[6] = {
 	20,
 	0,
 	16 + 1,