diff --git a/README.md b/README.md
index 8128d22..324b26d 100644
--- a/README.md
+++ b/README.md
@@ -74,7 +74,8 @@ println!("{}", serde_json::to_string_pretty(&schema).unwrap());
             "StringNewType": {
               "type": "string"
             }
-          }
+          },
+          "additionalProperties": false
         },
         {
           "type": "object",
@@ -97,7 +98,8 @@ println!("{}", serde_json::to_string_pretty(&schema).unwrap());
                 }
               }
             }
-          }
+          },
+          "additionalProperties": false
         }
       ]
     }
diff --git a/docs/_includes/examples/custom_settings.schema.json b/docs/_includes/examples/custom_settings.schema.json
index 36d9f17..59939be 100644
--- a/docs/_includes/examples/custom_settings.schema.json
+++ b/docs/_includes/examples/custom_settings.schema.json
@@ -35,7 +35,8 @@
             "StringNewType": {
               "type": "string"
             }
-          }
+          },
+          "additionalProperties": false
         },
         {
           "type": "object",
@@ -58,7 +59,8 @@
                 }
               }
             }
-          }
+          },
+          "additionalProperties": false
         }
       ]
     }
diff --git a/docs/_includes/examples/doc_comments.schema.json b/docs/_includes/examples/doc_comments.schema.json
index 7cc468f..0f3405c 100644
--- a/docs/_includes/examples/doc_comments.schema.json
+++ b/docs/_includes/examples/doc_comments.schema.json
@@ -44,7 +44,8 @@
             "StringNewType": {
               "type": "string"
             }
-          }
+          },
+          "additionalProperties": false
         },
         {
           "description": "A struct-like enum variant which contains some floats",
@@ -69,7 +70,8 @@
                 }
               }
             }
-          }
+          },
+          "additionalProperties": false
         }
       ]
     }
diff --git a/docs/_includes/examples/main.schema.json b/docs/_includes/examples/main.schema.json
index a658248..737bcbc 100644
--- a/docs/_includes/examples/main.schema.json
+++ b/docs/_includes/examples/main.schema.json
@@ -37,7 +37,8 @@
             "StringNewType": {
               "type": "string"
             }
-          }
+          },
+          "additionalProperties": false
         },
         {
           "type": "object",
@@ -60,7 +61,8 @@
                 }
               }
             }
-          }
+          },
+          "additionalProperties": false
         }
       ]
     }
diff --git a/schemars/examples/custom_settings.schema.json b/schemars/examples/custom_settings.schema.json
index 36d9f17..59939be 100644
--- a/schemars/examples/custom_settings.schema.json
+++ b/schemars/examples/custom_settings.schema.json
@@ -35,7 +35,8 @@
             "StringNewType": {
               "type": "string"
             }
-          }
+          },
+          "additionalProperties": false
         },
         {
           "type": "object",
@@ -58,7 +59,8 @@
                 }
               }
             }
-          }
+          },
+          "additionalProperties": false
         }
       ]
     }
diff --git a/schemars/examples/doc_comments.schema.json b/schemars/examples/doc_comments.schema.json
index 7cc468f..0f3405c 100644
--- a/schemars/examples/doc_comments.schema.json
+++ b/schemars/examples/doc_comments.schema.json
@@ -44,7 +44,8 @@
             "StringNewType": {
               "type": "string"
             }
-          }
+          },
+          "additionalProperties": false
         },
         {
           "description": "A struct-like enum variant which contains some floats",
@@ -69,7 +70,8 @@
                 }
               }
             }
-          }
+          },
+          "additionalProperties": false
         }
       ]
     }
diff --git a/schemars/examples/main.schema.json b/schemars/examples/main.schema.json
index a658248..737bcbc 100644
--- a/schemars/examples/main.schema.json
+++ b/schemars/examples/main.schema.json
@@ -37,7 +37,8 @@
             "StringNewType": {
               "type": "string"
             }
-          }
+          },
+          "additionalProperties": false
         },
         {
           "type": "object",
@@ -60,7 +61,8 @@
                 }
               }
             }
-          }
+          },
+          "additionalProperties": false
         }
       ]
     }
diff --git a/schemars/src/lib.rs b/schemars/src/lib.rs
index 907572b..a4372f8 100644
--- a/schemars/src/lib.rs
+++ b/schemars/src/lib.rs
@@ -69,7 +69,8 @@ println!("{}", serde_json::to_string_pretty(&schema).unwrap());
                         "StringNewType": {
                             "type": "string"
                         }
-                    }
+                    },
+                    "additionalProperties": false
                 },
                 {
                     "type": "object",
@@ -92,7 +93,8 @@ println!("{}", serde_json::to_string_pretty(&schema).unwrap());
                                 }
                             }
                         }
-                    }
+                    },
+                    "additionalProperties": false
                 }
             ]
         }