diff --git a/HamShield.cpp b/HamShield.cpp
index 35dbf82..48cf13b 100644
--- a/HamShield.cpp
+++ b/HamShield.cpp
@@ -16,13 +16,13 @@ HamShield *HamShield::sHamShield = NULL;
 
 /* channel lookup tables */
 
-uint32_t FRS[] PROGMEM = {0,462562,462587,462612,462637,462662,462687,462712,467562,467587,467612,467637,467662,467687,467712};
+const uint32_t FRS[] PROGMEM = {0,462562,462587,462612,462637,462662,462687,462712,467562,467587,467612,467637,467662,467687,467712};
 
-uint32_t GMRS[] PROGMEM = {0,462550,462575,462600,462625,462650,462675,462700,462725};
+const uint32_t GMRS[] PROGMEM = {0,462550,462575,462600,462625,462650,462675,462700,462725};
 
-uint32_t MURS[] PROGMEM = {0,151820,151880,151940,154570,154600};
+const uint32_t MURS[] PROGMEM = {0,151820,151880,151940,154570,154600};
 
-uint32_t WX[] PROGMEM = {0,162550,162400,162475,162425,162450,162500,162525};
+const uint32_t WX[] PROGMEM = {0,162550,162400,162475,162425,162450,162500,162525};
 
 /* morse code lookup table */
 // This is the Morse table in reverse binary format.