diff --git a/glcdfont.c b/glcdfont.c
index e24ed4e..2d9d3a9 100644
--- a/glcdfont.c
+++ b/glcdfont.c
@@ -10,7 +10,7 @@
  
 // Standard ASCII 5x7 font
 
-static unsigned char  font[] PROGMEM = {
+static const unsigned char font[] PROGMEM = {
         0x00, 0x00, 0x00, 0x00, 0x00,   
 	0x3E, 0x5B, 0x4F, 0x5B, 0x3E, 	
 	0x3E, 0x6B, 0x4F, 0x6B, 0x3E,