diff --git a/engines/toon/audio.cpp b/engines/toon/audio.cpp
index d76a63c1ae9..0003bb19729 100644
--- a/engines/toon/audio.cpp
+++ b/engines/toon/audio.cpp
@@ -29,10 +29,10 @@
 
 namespace Toon {
 
-static int ADPCM_index[8] = {
+static const int ADPCM_index[8] = {
 	-1, -1, -1, -1, 2 , 4 , 6 , 8
 };
-static int ADPCM_table[89] = {
+static const int ADPCM_table[89] = {
 	7,     8,     9,     10,    11,    12,    13,    14,    16,    17,
 	19,    21,    23,    25,    28,    31,    34,    37,    41,    45,
 	50,    55,    60,    66,    73,    80,    88,    97,    107,   118,