diff --git a/README.md b/README.md
index 281ccb3..cd4989c 100644
--- a/README.md
+++ b/README.md
@@ -67,7 +67,7 @@ After starting up, most of the screen will be empty.
   * When all memtest passes have completed, there will be an additional `=` character left of these chars.
   * When the memtest routine was interrupted by an NMI, there will be a `!` instead.
 * When the screen is not cleared (filled with random characters), and the first line starts with `ZF***ZF` (`*` being other seemingly random characters), a fault in the first few bytes of the zero page were detected.  Since the memtest uses this area to store its state, the test is terminated prematurely.
-  * The tree characters in between the two `ZF`s are, from left to right, the zeropage address byte, the value written, the value read back.
+  * The three characters in between the two `ZF`s are, from left to right, the zeropage address byte, the value written, the value read back.
 
 ![Output Interpretation](pics/output_interpretation.jpg)