diff --git a/src/ch17-01-what-is-oo.md b/src/ch17-01-what-is-oo.md
index 86bf467a8c..fa0ec0c773 100644
--- a/src/ch17-01-what-is-oo.md
+++ b/src/ch17-01-what-is-oo.md
@@ -12,7 +12,7 @@ Rust supports it.
 
 The book *Design Patterns: Elements of Reusable Object-Oriented Software* by
 Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides (Addison-Wesley
-Professional, 1994) colloquially referred to as *The Gang of Four* book, is a
+Professional, 1994), colloquially referred to as *The Gang of Four* book, is a
 catalog of object-oriented design patterns. It defines OOP this way:
 
 > Object-oriented programs are made up of objects. An *object* packages both