diff --git a/03-bootsector-memory/README.md b/03-bootsector-memory/README.md
index c8d9b60..ccbf8a7 100644
--- a/03-bootsector-memory/README.md
+++ b/03-bootsector-memory/README.md
@@ -19,7 +19,7 @@ and see which ones work and why.
 First, we will define the X as data, with a label:
 ```nasm
 the_secret:
-    db "X"
+    db 'X'
 ```
 
 Then we will try to access `the_secret` in many different ways:
diff --git a/03-bootsector-memory/boot_sect_memory.asm b/03-bootsector-memory/boot_sect_memory.asm
index 7218841..54006dd 100644
--- a/03-bootsector-memory/boot_sect_memory.asm
+++ b/03-bootsector-memory/boot_sect_memory.asm
@@ -44,7 +44,7 @@ jmp $ ; infinite loop
 the_secret:
     ; ASCII code 0x58 ('X') is stored just before the zero-padding.
     ; On this code that is at byte 0x2d (check it out using 'xxd file.bin')
-    db "X"
+    db 'X'
 
 ; zero padding and magic bios number
 times 510-($-$$) db 0
diff --git a/03-bootsector-memory/boot_sect_memory_org.asm b/03-bootsector-memory/boot_sect_memory_org.asm
index de5193c..6400843 100644
--- a/03-bootsector-memory/boot_sect_memory_org.asm
+++ b/03-bootsector-memory/boot_sect_memory_org.asm
@@ -40,7 +40,7 @@ jmp $ ; infinite loop
 the_secret:
     ; ASCII code 0x58 ('X') is stored just before the zero-padding.
     ; On this code that is at byte 0x2d (check it out using 'xxd file.bin')
-    db "X"
+    db 'X'
 
 ; zero padding and magic bios number
 times 510-($-$$) db 0