diff --git a/cmd_parser.c b/cmd_parser.c
index 27eb596..bf09cdf 100644
--- a/cmd_parser.c
+++ b/cmd_parser.c
@@ -60,7 +60,12 @@ __code uint8_t phys_to_log_port[6] = {
 
 inline uint8_t isletter(uint8_t l)
 {
-	return (l >= 'a' && l <= 'z') || (l >= 'A' && l <= 'Z');
+	// return (l >= 'a' && l <= 'z') || (l >= 'A' && l <= 'Z');
+
+	// Make it upper case
+	l |= 0x20;
+	l -= 'A';
+	return (l <= ('Z'-'A'));
 }
 
 
diff --git a/rtlplayground.mem b/rtlplayground.mem
index 7626c2d..cc92f39 100644
--- a/rtlplayground.mem
+++ b/rtlplayground.mem
@@ -26,4 +26,4 @@ Other memory:
    ---------------- -------- -------- -------- --------
    PAGED EXT. RAM                         0      256   
    EXTERNAL RAM     0x0001   0x1ae8    6888    16777216
-   ROM/EPROM/FLASH  0x0000   0x1c71b  47003    16777216
+   ROM/EPROM/FLASH  0x0000   0x1c6f2  46962    16777216