diff --git a/Doc/ref/ref4.tex b/Doc/ref/ref4.tex
index f16dc8e..6e893f1 100644
--- a/Doc/ref/ref4.tex
+++ b/Doc/ref/ref4.tex
@@ -32,7 +32,7 @@
 completed.
 
 A \dfn{scope}\index{scope} defines the visibility of a name within a
-block.  If a local variable is defined in a block, it's scope includes
+block.  If a local variable is defined in a block, its scope includes
 that block.  If the definition occurs in a function block, the scope
 extends to any blocks contained within the defining one, unless a
 contained block introduces a different binding for the name.  The