diff --git a/src/develop.rs b/src/develop.rs
index d15b1b05f..84ae64222 100644
--- a/src/develop.rs
+++ b/src/develop.rs
@@ -9,7 +9,6 @@ use crate::Target;
 use anyhow::{anyhow, bail, Context, Result};
 use cargo_options::heading;
 use fs_err as fs;
-use pep508_rs::{MarkerExpression, MarkerOperator, MarkerTree, MarkerValue};
 use regex::Regex;
 use std::path::Path;
 use std::path::PathBuf;
@@ -145,31 +144,23 @@ fn install_dependencies(
     install_backend: &InstallBackend,
 ) -> Result<()> {
     if !build_context.metadata23.requires_dist.is_empty() {
+        let mut extra_names = Vec::with_capacity(extras.len());
+        for extra in extras {
+            extra_names.push(
+                pep508_rs::ExtraName::new(extra.clone())
+                    .with_context(|| format!("invalid extra name: {extra}"))?,
+            );
+        }
         let mut args = vec!["install".to_string()];
         args.extend(build_context.metadata23.requires_dist.iter().map(|x| {
             let mut pkg = x.clone();
-            // Remove extra marker to make it installable with pip
-            // Keep in sync with `Metadata23::merge_pyproject_toml()`!
-            for extra in extras {
-                pkg.marker = pkg.marker.and_then(|marker| -> Option<MarkerTree> {
-                    match marker.clone() {
-                        MarkerTree::Expression(MarkerExpression {
-                            l_value: MarkerValue::Extra,
-                            operator: MarkerOperator::Equal,
-                            r_value: MarkerValue::QuotedString(extra_value),
-                        }) if &extra_value == extra => None,
-                        MarkerTree::And(and) => match &*and {
-                            [existing, MarkerTree::Expression(MarkerExpression {
-                                l_value: MarkerValue::Extra,
-                                operator: MarkerOperator::Equal,
-                                r_value: MarkerValue::QuotedString(extra_value),
-                            })] if extra_value == extra => Some(existing.clone()),
-                            _ => Some(marker),
-                        },
-                        _ => Some(marker),
-                    }
-                });
-            }
+            // Remove extra marker to make it installable with pip:
+            //
+            // * ` and extra == 'EXTRA_NAME'`
+            // * `; extra == 'EXTRA_NAME'`
+            //
+            // Keep in sync with `Metadata23::merge_pyproject_toml()`
+            pkg.marker = pkg.marker.simplify_extras(&extra_names);
             pkg.to_string()
         }));
         let status = install_backend
diff --git a/src/metadata.rs b/src/metadata.rs
index 760343d0c..827ab828c 100644
--- a/src/metadata.rs
+++ b/src/metadata.rs
@@ -3,7 +3,9 @@ use anyhow::{bail, format_err, Context, Result};
 use fs_err as fs;
 use indexmap::IndexMap;
 use pep440_rs::{Version, VersionSpecifiers};
-use pep508_rs::{MarkerExpression, MarkerOperator, MarkerTree, MarkerValue, Requirement};
+use pep508_rs::{
+    ExtraName, ExtraOperator, MarkerExpression, MarkerTree, MarkerValueExtra, Requirement,
+};
 use pyproject_toml::License;
 use regex::Regex;
 use serde::{Deserialize, Serialize};
@@ -291,16 +293,14 @@ impl Metadata23 {
                     for dep in deps {
                         let mut dep = dep.clone();
                         // Keep in sync with `develop()`!
-                        let new_extra = MarkerTree::Expression(MarkerExpression {
-                            l_value: MarkerValue::Extra,
-                            operator: MarkerOperator::Equal,
-                            r_value: MarkerValue::QuotedString(extra.to_string()),
-                        });
-                        if let Some(existing) = dep.marker.take() {
-                            dep.marker = Some(MarkerTree::And(vec![existing, new_extra]));
-                        } else {
-                            dep.marker = Some(new_extra);
-                        }
+                        let new_extra = MarkerExpression::Extra {
+                            operator: ExtraOperator::Equal,
+                            name: MarkerValueExtra::Extra(
+                                ExtraName::new(extra.clone())
+                                    .with_context(|| format!("invalid extra name: {extra}"))?,
+                            ),
+                        };
+                        dep.marker.and(MarkerTree::expression(new_extra));
                         self.requires_dist.push(dep);
                     }
                 }
diff --git a/src/pyproject_toml.rs b/src/pyproject_toml.rs
index f338b03ed..b4cede944 100644
--- a/src/pyproject_toml.rs
+++ b/src/pyproject_toml.rs
@@ -627,11 +627,13 @@ mod tests {
         let inner_error = outer_error.source().unwrap();
 
         let expected = expect![[r#"
-            TOML parse error at line 7, column 17
-              |
-            7 | license-files = [ "license.txt",]
-              |                 ^^^^^^^^^^^^^^^^^
-            wanted string or table
+            TOML parse error at line 10, column 16
+               |
+            10 | dependencies = [ "packaging", "...",]
+               |                ^^^^^^^^^^^^^^^^^^^^^^
+            URL requirement must be preceded by a package name. Add the name of the package before the URL (e.g., `package_name @ /path/to/file`).
+            ...
+            ^^^
         "#]];
         expected.assert_eq(&inner_error.to_string());
     }