diff --git a/Cargo.toml b/Cargo.toml
index c1e8ec9..86dea63 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,15 +11,14 @@ license = "MIT"
 edition = "2018"
 
 [dependencies]
-failure = "0.1"
-semver = "0.11"
+semver = "1.0"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
-serde_yaml = "0.8"
+serde_yaml = "0.9"
 thiserror = "1.0"
 url = { version = "2.0", features = ["serde"] }
 
 [dev-dependencies]
 anyhow = "1.0"
-pretty_assertions = "0.6"
-serde_test = "1.0.117"
+pretty_assertions = "1.0"
+serde_test = "1.0"
diff --git a/src/error.rs b/src/error.rs
index 8e91aae..2b1179a 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -1,6 +1,6 @@
 //! Error types
 
-use semver::{SemVerError, Version};
+use semver::{Error as SemVerError, Version};
 use serde_json::Error as JsonError;
 use serde_yaml::Error as YamlError;
 use std::io::Error as IoError;
diff --git a/src/v2/schema.rs b/src/v2/schema.rs
index 374b19c..c6f6251 100644
--- a/src/v2/schema.rs
+++ b/src/v2/schema.rs
@@ -3,21 +3,16 @@ use std::collections::BTreeMap;
 
 // http://json.schemastore.org/swagger-2.0
 
-#[derive(Clone, Debug, Deserialize, Serialize, PartialEq)]
+#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Default)]
 #[serde(rename_all = "lowercase")]
 pub enum Scheme {
+    #[default]
     Http,
     Https,
     Ws,
     Wss,
 }
 
-impl Default for Scheme {
-    fn default() -> Self {
-        Scheme::Http
-    }
-}
-
 /// top level document
 #[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Default)]
 #[serde(rename_all = "camelCase")]
diff --git a/src/v3_0/extension.rs b/src/v3_0/extension.rs
index d1280ce..4c07c3b 100644
--- a/src/v3_0/extension.rs
+++ b/src/v3_0/extension.rs
@@ -7,7 +7,7 @@ use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
 /// Contains openapi specification extensions
 /// see https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.1.md#specificationExtensions
-#[derive(Debug, Eq, PartialEq, Clone)]
+#[derive(Debug, Eq, PartialEq, Clone, Default)]
 pub struct Extensions(HashMap<String, serde_json::Value>);
 
 impl Extensions {
@@ -26,11 +26,6 @@ impl Extensions {
     }
 }
 
-impl Default for Extensions {
-    fn default() -> Self {
-        Self(HashMap::new())
-    }
-}
 
 impl<'de> Deserialize<'de> for Extensions {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>