diff --git a/reference.htm b/reference.htm
index 0428f55..5a13096 100644
--- a/reference.htm
+++ b/reference.htm
@@ -119,7 +119,7 @@ This is intended as a quick reference for the <a href="index.htm">Applesoft BASI
 <dl>
     <dt>GR<dd>Set display to lores mode, clear screen
     <dt>COLOR= <var>expr</var><dd>Set lores color (0...15)
-    <dt>PLOT <var>expr</var>, <var>expr</var><dd>Plot lores point (x = 0...39, y = 0...40/48)
+    <dt>PLOT <var>expr</var>, <var>expr</var><dd>Plot lores point (x = 0...39, y = 0...39/47)
     <dt>HLIN <var>expr</var>, <var>expr</var> AT <var>expr</var><dd>Plot horizontal line (x1, x2 at y)
     <dt>VLIN <var>expr</var>, <var>expr</var> AT <var>expr</var><dd>Plot vertical line (y1, y2 at x)
 </dl>