diff --git a/Marlin/speed_lookuptable.h b/Marlin/speed_lookuptable.h
index ab3a076f14..45607bcb0c 100644
--- a/Marlin/speed_lookuptable.h
+++ b/Marlin/speed_lookuptable.h
@@ -3,7 +3,7 @@
 
 #include "Marlin.h"
 
-uint16_t speed_lookuptable_fast[256][2] PROGMEM = {\
+const uint16_t speed_lookuptable_fast[256][2] PROGMEM = {\
 { 62500, 55556}, { 6944, 3268}, { 3676, 1176}, { 2500, 607}, { 1893, 369}, { 1524, 249}, { 1275, 179}, { 1096, 135}, 
 { 961, 105}, { 856, 85}, { 771, 69}, { 702, 58}, { 644, 49}, { 595, 42}, { 553, 37}, { 516, 32}, 
 { 484, 28}, { 456, 25}, { 431, 23}, { 408, 20}, { 388, 19}, { 369, 16}, { 353, 16}, { 337, 14}, 
@@ -38,7 +38,7 @@ uint16_t speed_lookuptable_fast[256][2] PROGMEM = {\
 { 31, 0}, { 31, 0}, { 31, 0}, { 31, 1}, { 30, 0}, { 30, 0}, { 30, 0}, { 30, 0}
 };
 
-uint16_t speed_lookuptable_slow[256][2] PROGMEM = {\
+const uint16_t speed_lookuptable_slow[256][2] PROGMEM = {\
 { 62500, 12500}, { 50000, 8334}, { 41666, 5952}, { 35714, 4464}, { 31250, 3473}, { 27777, 2777}, { 25000, 2273}, { 22727, 1894}, 
 { 20833, 1603}, { 19230, 1373}, { 17857, 1191}, { 16666, 1041}, { 15625, 920}, { 14705, 817}, { 13888, 731}, { 13157, 657}, 
 { 12500, 596}, { 11904, 541}, { 11363, 494}, { 10869, 453}, { 10416, 416}, { 10000, 385}, { 9615, 356}, { 9259, 331},