diff --git a/identity-map/README.md b/identity-map/README.md
index a5bb4d386..6594f54ed 100644
--- a/identity-map/README.md
+++ b/identity-map/README.md
@@ -1,6 +1,6 @@
 ---
 title: Identity Map
-categories: Behavioral
+category: Behavioral
 language: en
 tags:
 - Performance
diff --git a/intercepting-filter/README.md b/intercepting-filter/README.md
index f5aef5d03..aef71f4f5 100644
--- a/intercepting-filter/README.md
+++ b/intercepting-filter/README.md
@@ -1,6 +1,6 @@
 ---
 title: Intercepting Filter
-categories: Behavioral
+category: Behavioral
 language: en
 tags:
  - Decoupling
diff --git a/interpreter/README.md b/interpreter/README.md
index 61bf7501a..99d3c30e5 100644
--- a/interpreter/README.md
+++ b/interpreter/README.md
@@ -1,6 +1,6 @@
 ---
 title: Interpreter
-categories: Behavioral
+category: Behavioral
 language: en
 tags:
  - Gang of Four
diff --git a/iterator/README.md b/iterator/README.md
index 3f36d0070..b49151eab 100644
--- a/iterator/README.md
+++ b/iterator/README.md
@@ -1,6 +1,6 @@
 ---
 title: Iterator
-categories: Behavioral
+category: Behavioral
 language: en
 tags:
  - Gang of Four