diff --git a/pyo3-build-config/src/impl_.rs b/pyo3-build-config/src/impl_.rs
index 24e8a76401f..8fde0412971 100644
--- a/pyo3-build-config/src/impl_.rs
+++ b/pyo3-build-config/src/impl_.rs
@@ -69,7 +69,7 @@ pub fn target_triple_from_env() -> Triple {
 ///
 /// When the `PYO3_NO_PYTHON` variable is set, or during cross compile situations, then alternative
 /// strategies are used to populate this type.
-#[cfg_attr(test, derive(Debug, PartialEq))]
+#[cfg_attr(test, derive(Debug, PartialEq, Eq))]
 pub struct InterpreterConfig {
     /// The Python implementation flavor.
     ///
@@ -634,7 +634,7 @@ impl FromStr for PythonVersion {
     }
 }
 
-#[derive(Debug, Copy, Clone, PartialEq)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
 pub enum PythonImplementation {
     CPython,
     PyPy,
@@ -742,7 +742,7 @@ fn require_libdir_for_target(target: &Triple) -> bool {
 ///
 /// Usually this is collected from the environment (i.e. `PYO3_CROSS_*` and `CARGO_CFG_TARGET_*`)
 /// when a cross-compilation configuration is detected.
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Eq)]
 pub struct CrossCompileConfig {
     /// The directory containing the Python library to link against.
     pub lib_dir: Option<PathBuf>,
@@ -1036,7 +1036,7 @@ impl FromStr for BuildFlag {
 /// is the equivalent of `#ifdef {varname}` in C.
 ///
 /// see Misc/SpecialBuilds.txt in the python source for what these mean.
-#[cfg_attr(test, derive(Debug, PartialEq))]
+#[cfg_attr(test, derive(Debug, PartialEq, Eq))]
 #[derive(Clone, Default)]
 pub struct BuildFlags(pub HashSet<BuildFlag>);
 
diff --git a/pyo3-macros-backend/src/attributes.rs b/pyo3-macros-backend/src/attributes.rs
index 42efade0f34..901927430fb 100644
--- a/pyo3-macros-backend/src/attributes.rs
+++ b/pyo3-macros-backend/src/attributes.rs
@@ -40,7 +40,7 @@ pub struct KeywordAttribute<K, V> {
 
 /// A helper type which parses the inner type via a literal string
 /// e.g. LitStrValue<Path> -> parses "some::path" in quotes.
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct LitStrValue<T>(pub T);
 
 impl<T: Parse> Parse for LitStrValue<T> {
@@ -57,7 +57,7 @@ impl<T: ToTokens> ToTokens for LitStrValue<T> {
 }
 
 /// A helper type which parses a name via a literal string
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct NameLitStr(pub Ident);
 
 impl Parse for NameLitStr {
diff --git a/pyo3-macros-backend/src/pyfunction.rs b/pyo3-macros-backend/src/pyfunction.rs
index f3138e943e0..c97495b1b55 100644
--- a/pyo3-macros-backend/src/pyfunction.rs
+++ b/pyo3-macros-backend/src/pyfunction.rs
@@ -21,7 +21,7 @@ use syn::{
     token::Comma,
 };
 
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub enum Argument {
     PosOnlyArgsSeparator,
     VarArgsSeparator,
diff --git a/src/pycell.rs b/src/pycell.rs
index b42cbe37a24..11f05eb5018 100644
--- a/src/pycell.rs
+++ b/src/pycell.rs
@@ -964,7 +964,7 @@ impl<'a, T: PyClass<Frozen = False>> std::convert::TryFrom<&'a PyCell<T>>
 
 impl<T: PyClass<Frozen = False> + fmt::Debug> fmt::Debug for PyRefMut<'_, T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Debug::fmt(&*(self.deref()), f)
+        fmt::Debug::fmt(self.deref(), f)
     }
 }
 
diff --git a/src/types/string.rs b/src/types/string.rs
index d195f1d2c58..1cd7a1499a6 100644
--- a/src/types/string.rs
+++ b/src/types/string.rs
@@ -16,7 +16,7 @@ use std::str;
 /// Python internally stores strings in various representations. This enumeration
 /// represents those variations.
 #[cfg(all(not(Py_LIMITED_API), target_endian = "little"))]
-#[derive(Clone, Copy, Debug, PartialEq)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum PyStringData<'a> {
     /// UCS1 representation.
     Ucs1(&'a [u8]),