diff --git a/io.cpp b/io.cpp
index fa2e124..2bcf9bd 100644
--- a/io.cpp
+++ b/io.cpp
@@ -39,7 +39,7 @@ void io::load() {
 }
 
 // ascii map for scan-codes
-static const uint8_t scanmap[] = {
+static const uint8_t scanmap[] PROGMEM = {
 	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 	// 0x00
 	0xff, 0xff, 0xff, 0xff, 0xff, 0x09, 0x60, 0xff, 	// 0x08
 	0xff, 0xff, 0xff, 0xff, 0xff, 0x51, 0x31, 0xff, 	// 0x10
@@ -58,7 +58,7 @@ static const uint8_t scanmap[] = {
 	0xff, 0x2b, 0x33, 0x2d, 0x2a, 0x39, 0xff, 0xff, 	// 0x78
 };
 
-static const uint8_t shiftmap[] = {
+static const uint8_t shiftmap[] PROGMEM = {
 	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,		// 0x00
 	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,		// 0x08
 	0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x21, 0xff,		// 0x10
@@ -92,7 +92,7 @@ void io::up(uint8_t scan) {
 		_shift = false;
 		return;
 	}
-	enter(_shift? shiftmap[scan]: scanmap[scan]);
+	enter(_shift? pgm_read_byte(shiftmap + scan): pgm_read_byte(scanmap + scan));
 }
 
 void io::draw(char ch, int i, int j) {