diff --git a/src/body.rs b/src/body.rs
index e9be0b65..b2e5b5c2 100644
--- a/src/body.rs
+++ b/src/body.rs
@@ -219,7 +219,7 @@ impl Body {
     /// assert_eq!(&body.into_string().await.unwrap(), "Hello Nori");
     /// # Ok(()) }) }
     /// ```
-    pub async fn into_string(mut self) -> io::Result<String> {
+    pub async fn into_string(mut self) -> crate::Result<String> {
         let mut result = String::with_capacity(self.len().unwrap_or(0));
         self.read_to_string(&mut result).await?;
         Ok(result)
diff --git a/src/headers/headers.rs b/src/headers/headers.rs
index e7efba26..c4245e7d 100644
--- a/src/headers/headers.rs
+++ b/src/headers/headers.rs
@@ -58,22 +58,17 @@ impl Headers {
     ///
     /// Unlike `insert` this function will not override the contents of a header, but insert a
     /// header if there aren't any. Or else append to the existing list of headers.
-    pub fn append(
-        &mut self,
-        name: impl Into<HeaderName>,
-        values: impl ToHeaderValues,
-    ) -> crate::Result<()> {
+    pub fn append(&mut self, name: impl Into<HeaderName>, values: impl ToHeaderValues) {
         let name = name.into();
         match self.get_mut(name.clone()) {
             Some(headers) => {
-                let mut values: HeaderValues = values.to_header_values()?.collect();
+                let mut values: HeaderValues = values.to_header_values().unwrap().collect();
                 headers.append(&mut values);
             }
             None => {
                 self.insert(name, values);
             }
         }
-        Ok(())
     }
 
     /// Get a reference to a header.
@@ -194,9 +189,9 @@ mod tests {
         let non_static_header = HeaderName::from_str("hello")?;
 
         let mut headers = Headers::new();
-        headers.append(STATIC_HEADER, "foo0")?;
-        headers.append(static_header.clone(), "foo1")?;
-        headers.append(non_static_header.clone(), "foo2")?;
+        headers.append(STATIC_HEADER, "foo0");
+        headers.append(static_header.clone(), "foo1");
+        headers.append(non_static_header.clone(), "foo2");
 
         assert_eq!(headers[STATIC_HEADER], ["foo0", "foo1", "foo2",][..]);
         assert_eq!(headers[static_header], ["foo0", "foo1", "foo2",][..]);
diff --git a/src/request.rs b/src/request.rs
index 27aa73f9..89354738 100644
--- a/src/request.rs
+++ b/src/request.rs
@@ -304,7 +304,7 @@ impl Request {
     /// assert_eq!(&req.body_string().await.unwrap(), "Hello Nori");
     /// # Ok(()) }) }
     /// ```
-    pub async fn body_string(self) -> io::Result<String> {
+    pub async fn body_string(self) -> crate::Result<String> {
         self.body.into_string().await
     }
 
@@ -441,15 +441,11 @@ impl Request {
     /// use http_types::{Url, Method, Request};
     ///
     /// let mut req = Request::new(Method::Get, Url::parse("https://example.com")?);
-    /// req.append_header("Content-Type", "text/plain")?;
+    /// req.append_header("Content-Type", "text/plain");
     /// #
     /// # Ok(()) }
     /// ```
-    pub fn append_header(
-        &mut self,
-        name: impl Into<HeaderName>,
-        values: impl ToHeaderValues,
-    ) -> crate::Result<()> {
+    pub fn append_header(&mut self, name: impl Into<HeaderName>, values: impl ToHeaderValues) {
         self.headers.append(name, values)
     }
 
diff --git a/src/response.rs b/src/response.rs
index 79066a7f..a37b8f99 100644
--- a/src/response.rs
+++ b/src/response.rs
@@ -126,15 +126,11 @@ impl Response {
     /// use http_types::{Response, StatusCode};
     ///
     /// let mut res = Response::new(StatusCode::Ok);
-    /// res.append_header("Content-Type", "text/plain")?;
+    /// res.append_header("Content-Type", "text/plain");
     /// #
     /// # Ok(()) }
     /// ```
-    pub fn append_header(
-        &mut self,
-        name: impl Into<HeaderName>,
-        values: impl ToHeaderValues,
-    ) -> crate::Result<()> {
+    pub fn append_header(&mut self, name: impl Into<HeaderName>, values: impl ToHeaderValues) {
         self.headers.append(name, values)
     }
 
@@ -265,7 +261,7 @@ impl Response {
     /// assert_eq!(&res.body_string().await.unwrap(), "Hello Nori");
     /// # Ok(()) }) }
     /// ```
-    pub async fn body_string(self) -> io::Result<String> {
+    pub async fn body_string(self) -> crate::Result<String> {
         self.body.into_string().await
     }
 
diff --git a/src/security/mod.rs b/src/security/mod.rs
index a502f694..b19b3ab4 100644
--- a/src/security/mod.rs
+++ b/src/security/mod.rs
@@ -220,5 +220,5 @@ pub fn referrer_policy(mut headers: impl AsMut<Headers>, referrer: Option<Referr
 
     // We MUST allow for multiple Referrer-Policy headers to be set.
     // See: https://w3c.github.io/webappsec-referrer-policy/#unknown-policy-values example #13
-    headers.as_mut().append("Referrer-Policy", policy).unwrap();
+    headers.as_mut().append("Referrer-Policy", policy);
 }
diff --git a/src/trailers.rs b/src/trailers.rs
index 1b24857d..231a7472 100644
--- a/src/trailers.rs
+++ b/src/trailers.rs
@@ -108,15 +108,11 @@ impl Trailers {
     /// use http_types::Trailers;
     ///
     /// let mut trailers = Trailers::new();
-    /// trailers.append("Content-Type", "text/plain")?;
+    /// trailers.append("Content-Type", "text/plain");
     /// #
     /// # Ok(()) }
     /// ```
-    pub fn append(
-        &mut self,
-        name: impl Into<HeaderName>,
-        values: impl ToHeaderValues,
-    ) -> crate::Result<()> {
+    pub fn append(&mut self, name: impl Into<HeaderName>, values: impl ToHeaderValues) {
         self.headers.append(name, values)
     }