diff --git a/Cargo.toml b/Cargo.toml
index a0b23cb..adb39f6 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -29,7 +29,7 @@ path = "src/lib.rs"
 native-tls = "0.2.2"
 regex = "1.0"
 bufstream = "0.1"
-imap-proto = "0.7"
+imap-proto = "0.8"
 nom = "4.0"
 base64 = "0.10"
 chrono = "0.4"
diff --git a/src/client.rs b/src/client.rs
index 5540f4e..5aeb99b 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -14,7 +14,7 @@ use super::extensions;
 use super::parse::*;
 use super::types::*;
 
-static TAG_PREFIX: &'static str = "a";
+static TAG_PREFIX: &str = "a";
 const INITIAL_TAG: u32 = 0;
 const CR: u8 = 0x0d;
 const LF: u8 = 0x0a;
@@ -1620,7 +1620,7 @@ mod tests {
         );
         assert_eq!(capabilities.len(), 4);
         for e in expected_capabilities {
-            assert!(capabilities.has(e));
+            assert!(capabilities.has_str(e));
         }
     }
 
diff --git a/src/error.rs b/src/error.rs
index 6891406..ef89939 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -106,7 +106,7 @@ impl StdError for Error {
         }
     }
 
-    fn cause(&self) -> Option<&StdError> {
+    fn cause(&self) -> Option<&dyn StdError> {
         match *self {
             Error::Io(ref e) => Some(e),
             Error::Tls(ref e) => Some(e),
@@ -148,7 +148,7 @@ impl StdError for ParseError {
         }
     }
 
-    fn cause(&self) -> Option<&StdError> {
+    fn cause(&self) -> Option<&dyn StdError> {
         match *self {
             ParseError::Authentication(_, Some(ref e)) => Some(e),
             _ => None,
@@ -173,7 +173,7 @@ impl StdError for ValidateError {
         "Invalid character in input"
     }
 
-    fn cause(&self) -> Option<&StdError> {
+    fn cause(&self) -> Option<&dyn StdError> {
         None
     }
 }
diff --git a/src/parse.rs b/src/parse.rs
index 8b32c17..a2de763 100644
--- a/src/parse.rs
+++ b/src/parse.rs
@@ -342,7 +342,7 @@ mod tests {
         assert!(recv.try_recv().is_err());
         assert_eq!(capabilities.len(), 4);
         for e in expected_capabilities {
-            assert!(capabilities.has(e));
+            assert!(capabilities.has_str(e));
         }
     }
 
@@ -445,7 +445,7 @@ mod tests {
 
         assert_eq!(capabilities.len(), 4);
         for e in expected_capabilities {
-            assert!(capabilities.has(e));
+            assert!(capabilities.has_str(e));
         }
 
         assert_eq!(
diff --git a/src/types/capabilities.rs b/src/types/capabilities.rs
index 166bfa8..2cc3672 100644
--- a/src/types/capabilities.rs
+++ b/src/types/capabilities.rs
@@ -1,7 +1,9 @@
-use std::borrow::Borrow;
+use imap_proto::types::Capability;
 use std::collections::hash_set::Iter;
 use std::collections::HashSet;
-use std::hash::Hash;
+
+const IMAP4REV1_CAPABILITY: &str = "IMAP4rev1";
+const AUTH_CAPABILITY_PREFIX: &str = "AUTH=";
 
 /// From [section 7.2.1 of RFC 3501](https://tools.ietf.org/html/rfc3501#section-7.2.1).
 ///
@@ -31,21 +33,29 @@ use std::hash::Hash;
 pub struct Capabilities(
     // Note that this field isn't *actually* 'static.
     // Rather, it is tied to the lifetime of the `ZeroCopy` that contains this `Name`.
-    pub(crate) HashSet<&'static str>,
+    pub(crate) HashSet<Capability<'static>>,
 );
 
 impl Capabilities {
     /// Check if the server has the given capability.
-    pub fn has<S: ?Sized>(&self, s: &S) -> bool
-    where
-        for<'a> &'a str: Borrow<S>,
-        S: Hash + Eq,
-    {
-        self.0.contains(s)
+    pub fn has<'a>(&self, cap: &Capability<'a>) -> bool {
+        self.0.contains(cap)
+    }
+
+    /// Check if the server has the given capability via str.
+    pub fn has_str<S: AsRef<str>>(&self, cap: S) -> bool {
+        let s = cap.as_ref();
+        if s == IMAP4REV1_CAPABILITY {
+            self.has(&Capability::Imap4rev1)
+        } else if s.starts_with(AUTH_CAPABILITY_PREFIX) {
+            self.has(&Capability::Auth(&s[AUTH_CAPABILITY_PREFIX.len()..]))
+        } else {
+            self.has(&Capability::Atom(s))
+        }
     }
 
     /// Iterate over all the server's capabilities
-    pub fn iter(&self) -> Iter<&str> {
+    pub fn iter(&self) -> Iter<Capability> {
         self.0.iter()
     }