diff --git a/ThermistorTable.double.h b/ThermistorTable.double.h
index 60c7bdba0..3de3423c7 100644
--- a/ThermistorTable.double.h
+++ b/ThermistorTable.double.h
@@ -35,7 +35,7 @@
 // Must be the same for all tables.
 #define NUMTEMPS 102
 
-uint16_t temptable[NUMTABLES][NUMTEMPS][2] PROGMEM = {
+uint16_t const temptable[NUMTABLES][NUMTEMPS][2] PROGMEM = {
 
 // Table for the Extruder.
 // Thermistor: EPCOS B57560G104F
diff --git a/ThermistorTable.single.h b/ThermistorTable.single.h
index 68d8ba86a..f788a3708 100644
--- a/ThermistorTable.single.h
+++ b/ThermistorTable.single.h
@@ -35,7 +35,7 @@
 // Must be the same for all tables.
 #define NUMTEMPS 20
 
-uint16_t temptable[NUMTABLES][NUMTEMPS][2] PROGMEM = {
+uint16_t const temptable[NUMTABLES][NUMTEMPS][2] PROGMEM = {
 
 // Table for the Extruder.
 // Thermistor: unknown