diff --git a/crates_io_tarball/src/lib.rs b/crates_io_tarball/src/lib.rs
index d73074f0d0..309ff5779a 100644
--- a/crates_io_tarball/src/lib.rs
+++ b/crates_io_tarball/src/lib.rs
@@ -5,8 +5,9 @@ extern crate claims;
 #[cfg(any(feature = "builder", test))]
 pub use crate::builder::TarballBuilder;
 use crate::limit_reader::LimitErrorReader;
-pub use crate::manifest::Manifest;
+use crate::manifest::validate_manifest;
 pub use crate::vcs_info::CargoVcsInfo;
+pub use cargo_toml::Manifest;
 use flate2::read::GzDecoder;
 use std::io::Read;
 use std::path::Path;
@@ -35,7 +36,7 @@ pub enum TarballError {
     #[error("Cargo.toml manifest is missing")]
     MissingManifest,
     #[error("Cargo.toml manifest is invalid: {0}")]
-    InvalidManifest(#[source] toml::de::Error),
+    InvalidManifest(#[from] cargo_toml::Error),
     #[error(transparent)]
     IO(#[from] std::io::Error),
 }
@@ -97,7 +98,11 @@ pub fn process_tarball<R: Read>(
             // erroring if it cannot be read.
             let mut contents = String::new();
             entry.read_to_string(&mut contents)?;
-            manifest = Some(toml::from_str(&contents).map_err(TarballError::InvalidManifest)?);
+            manifest = Some({
+                let manifest = Manifest::from_str(&contents)?;
+                validate_manifest(&manifest)?;
+                manifest
+            });
         }
     }
 
@@ -178,10 +183,10 @@ repository = "https://github.com/foo/bar"
         let limit = 512 * 1024 * 1024;
 
         let tarball_info = assert_ok!(process_tarball("foo-0.0.1", &*tarball, limit));
-        let package = tarball_info.manifest.package;
-        assert_some_eq!(package.readme.as_path(), Path::new("README.md"));
-        assert_some_eq!(package.repository, "https://github.com/foo/bar");
-        assert_some_eq!(package.rust_version, "1.59");
+        let package = assert_some!(tarball_info.manifest.package);
+        assert_some_eq!(package.readme().as_path(), Path::new("README.md"));
+        assert_some_eq!(package.repository(), "https://github.com/foo/bar");
+        assert_some_eq!(package.rust_version(), "1.59");
     }
 
     #[test]
@@ -200,8 +205,8 @@ repository = "https://github.com/foo/bar"
         let limit = 512 * 1024 * 1024;
 
         let tarball_info = assert_ok!(process_tarball("foo-0.0.1", &*tarball, limit));
-        let package = tarball_info.manifest.package;
-        assert_some_eq!(package.rust_version, "1.23");
+        let package = assert_some!(tarball_info.manifest.package);
+        assert_some_eq!(package.rust_version(), "1.23");
     }
 
     #[test]
@@ -219,8 +224,8 @@ repository = "https://github.com/foo/bar"
         let limit = 512 * 1024 * 1024;
 
         let tarball_info = assert_ok!(process_tarball("foo-0.0.1", &*tarball, limit));
-        let package = tarball_info.manifest.package;
-        assert_matches!(package.readme, OptionalFile::Flag(true));
+        let package = assert_some!(tarball_info.manifest.package);
+        assert_matches!(package.readme(), OptionalFile::Flag(true));
     }
 
     #[test]
@@ -239,8 +244,8 @@ repository = "https://github.com/foo/bar"
         let limit = 512 * 1024 * 1024;
 
         let tarball_info = assert_ok!(process_tarball("foo-0.0.1", &*tarball, limit));
-        let package = tarball_info.manifest.package;
-        assert_matches!(package.readme, OptionalFile::Flag(false));
+        let package = assert_some!(tarball_info.manifest.package);
+        assert_matches!(package.readme(), OptionalFile::Flag(false));
     }
 
     #[test]
@@ -260,7 +265,7 @@ repository = "https://github.com/foo/bar"
         let limit = 512 * 1024 * 1024;
 
         let tarball_info = assert_ok!(process_tarball("foo-0.0.1", &*tarball, limit));
-        let package = tarball_info.manifest.package;
-        assert_some_eq!(package.repository, "https://github.com/foo/bar");
+        let package = assert_some!(tarball_info.manifest.package);
+        assert_some_eq!(package.repository(), "https://github.com/foo/bar");
     }
 }
diff --git a/crates_io_tarball/src/manifest.rs b/crates_io_tarball/src/manifest.rs
index 5726f2eada..b84edbb44b 100644
--- a/crates_io_tarball/src/manifest.rs
+++ b/crates_io_tarball/src/manifest.rs
@@ -1,44 +1,89 @@
-use cargo_toml::OptionalFile;
-use derive_deref::Deref;
-use serde::{de, Deserialize, Deserializer};
-
-#[derive(Debug, Deserialize)]
-pub struct Manifest {
-    #[serde(alias = "project")]
-    pub package: Package,
-}
-
-#[derive(Debug, Deserialize)]
-#[serde(rename_all = "kebab-case")]
-pub struct Package {
-    pub name: String,
-    pub version: String,
-    #[serde(default)]
-    pub readme: OptionalFile,
-    pub repository: Option<String>,
-    pub rust_version: Option<RustVersion>,
-}
-
-#[derive(Debug, Deref)]
-pub struct RustVersion(String);
-
-impl PartialEq<&str> for RustVersion {
-    fn eq(&self, other: &&str) -> bool {
-        self.0.eq(other)
-    }
-}
-
-impl<'de> Deserialize<'de> for RustVersion {
-    fn deserialize<D: Deserializer<'de>>(d: D) -> Result<RustVersion, D::Error> {
-        let s = String::deserialize(d)?;
-        match semver::VersionReq::parse(&s) {
-            // Exclude semver operators like `^` and pre-release identifiers
-            Ok(_) if s.chars().all(|c| c.is_ascii_digit() || c == '.') => Ok(RustVersion(s)),
-            Ok(_) | Err(..) => {
-                let value = de::Unexpected::Str(&s);
-                let expected = "a valid rust_version";
-                Err(de::Error::invalid_value(value, &expected))
-            }
-        }
+use cargo_toml::{Dependency, DepsSet, Error, Inheritable, Manifest, Package};
+
+pub fn validate_manifest(manifest: &Manifest) -> Result<(), Error> {
+    let package = manifest.package.as_ref();
+
+    // Check that a `[package]` table exists in the manifest, since crates.io
+    // does not accept workspace manifests.
+    let package = package.ok_or(Error::Other("missing field `package`"))?;
+
+    validate_package(package)?;
+
+    // These checks ensure that dependency workspace inheritance has been
+    // normalized by cargo before publishing.
+    if manifest.dependencies.is_inherited()
+        || manifest.dev_dependencies.is_inherited()
+        || manifest.build_dependencies.is_inherited()
+    {
+        return Err(Error::InheritedUnknownValue);
+    }
+
+    Ok(())
+}
+
+pub fn validate_package(package: &Package) -> Result<(), Error> {
+    // These checks ensure that package field workspace inheritance has been
+    // normalized by cargo before publishing.
+    if package.edition.is_inherited()
+        || package.rust_version.is_inherited()
+        || package.version.is_inherited()
+        || package.authors.is_inherited()
+        || package.description.is_inherited()
+        || package.homepage.is_inherited()
+        || package.documentation.is_inherited()
+        || package.readme.is_inherited()
+        || package.keywords.is_inherited()
+        || package.categories.is_inherited()
+        || package.exclude.is_inherited()
+        || package.include.is_inherited()
+        || package.license.is_inherited()
+        || package.license_file.is_inherited()
+        || package.repository.is_inherited()
+        || package.publish.is_inherited()
+    {
+        return Err(Error::InheritedUnknownValue);
+    }
+
+    // Check that the `rust-version` field has a valid value, if it exists.
+    if let Some(rust_version) = package.rust_version() {
+        validate_rust_version(rust_version)?;
+    }
+
+    Ok(())
+}
+
+trait IsInherited {
+    fn is_inherited(&self) -> bool;
+}
+
+impl<T> IsInherited for Inheritable<T> {
+    fn is_inherited(&self) -> bool {
+        !self.is_set()
+    }
+}
+
+impl<T: IsInherited> IsInherited for Option<T> {
+    fn is_inherited(&self) -> bool {
+        self.as_ref().map(|it| it.is_inherited()).unwrap_or(false)
+    }
+}
+
+impl IsInherited for Dependency {
+    fn is_inherited(&self) -> bool {
+        matches!(self, Dependency::Inherited(_))
+    }
+}
+
+impl IsInherited for DepsSet {
+    fn is_inherited(&self) -> bool {
+        self.iter().any(|(_key, dep)| dep.is_inherited())
+    }
+}
+
+pub fn validate_rust_version(value: &str) -> Result<(), Error> {
+    match semver::VersionReq::parse(value) {
+        // Exclude semver operators like `^` and pre-release identifiers
+        Ok(_) if value.chars().all(|c| c.is_ascii_digit() || c == '.') => Ok(()),
+        Ok(_) | Err(..) => Err(Error::Other("invalid `rust-version` value")),
     }
 }
diff --git a/src/admin/render_readmes.rs b/src/admin/render_readmes.rs
index 97ad253fb6..9f21460939 100644
--- a/src/admin/render_readmes.rs
+++ b/src/admin/render_readmes.rs
@@ -177,11 +177,14 @@ fn render_pkg_readme<R: Read>(mut archive: Archive<R>, pkg_name: &str) -> anyhow
         let contents = find_file_by_path(&mut entries, Path::new(&path))
             .context("Failed to read Cargo.toml file")?;
 
-        toml::from_str(&contents).context("Failed to parse manifest file")?
+        Manifest::from_str(&contents).context("Failed to parse manifest file")?
+
+        // We don't call `validate_manifest()` here since the additional validation is not needed
+        // and it would prevent us from reading a couple of legacy crate files.
     };
 
     let rendered = {
-        let readme = manifest.package.readme;
+        let readme = manifest.package().readme();
         if !readme.is_some() {
             return Ok("".to_string());
         }
@@ -198,7 +201,7 @@ fn render_pkg_readme<R: Read>(mut archive: Archive<R>, pkg_name: &str) -> anyhow
         text_to_html(
             &contents,
             &readme_path,
-            manifest.package.repository.as_deref(),
+            manifest.package().repository(),
             pkg_path_in_vcs,
         )
     };
diff --git a/src/controllers/krate/publish.rs b/src/controllers/krate/publish.rs
index a0354ce69c..c6d0c1b5dc 100644
--- a/src/controllers/krate/publish.rs
+++ b/src/controllers/krate/publish.rs
@@ -197,8 +197,8 @@ pub async fn publish(app: AppState, req: BytesRequest) -> AppResult<Json<GoodCra
 
             let rust_version = tarball_info
                 .manifest
-                .package
-                .rust_version
+                .package()
+                .rust_version()
                 .map(|rv| rv.deref().to_string());
 
             // Persist the new version of this crate
diff --git a/src/tests/krate/publish.rs b/src/tests/krate/publish.rs
index 413a3aa897..0a34259e61 100644
--- a/src/tests/krate/publish.rs
+++ b/src/tests/krate/publish.rs
@@ -1291,7 +1291,7 @@ fn invalid_manifest() {
     assert_eq!(response.status(), StatusCode::OK);
     assert_eq!(
         response.into_json(),
-        json!({ "errors": [{ "detail": "failed to parse `Cargo.toml` manifest file\n\nTOML parse error at line 1, column 1\n  |\n1 | \n  | ^\nmissing field `package`\n" }] })
+        json!({ "errors": [{ "detail": "failed to parse `Cargo.toml` manifest file\n\nmissing field `name`\n" }] })
     );
 }
 
@@ -1339,7 +1339,7 @@ fn invalid_rust_version() {
     assert_eq!(response.status(), StatusCode::OK);
     assert_eq!(
         response.into_json(),
-        json!({ "errors": [{ "detail": "failed to parse `Cargo.toml` manifest file\n\nTOML parse error at line 4, column 16\n  |\n4 | rust-version = \"\"\n  |                ^^\ninvalid value: string \"\", expected a valid rust_version\n" }] })
+        json!({ "errors": [{ "detail": "failed to parse `Cargo.toml` manifest file\n\ninvalid `rust-version` value" }] })
     );
 
     let tarball = TarballBuilder::new("foo", "1.0.0")
@@ -1352,6 +1352,40 @@ fn invalid_rust_version() {
     assert_eq!(response.status(), StatusCode::OK);
     assert_eq!(
         response.into_json(),
-        json!({ "errors": [{ "detail": "failed to parse `Cargo.toml` manifest file\n\nTOML parse error at line 4, column 16\n  |\n4 | rust-version = \"1.0.0-beta.2\"\n  |                ^^^^^^^^^^^^^^\ninvalid value: string \"1.0.0-beta.2\", expected a valid rust_version\n" }] })
+        json!({ "errors": [{ "detail": "failed to parse `Cargo.toml` manifest file\n\ninvalid `rust-version` value" }] })
+    );
+}
+
+#[test]
+fn workspace_inheritance() {
+    let (_app, _anon, _cookie, token) = TestApp::full().with_token();
+
+    let tarball = TarballBuilder::new("foo", "1.0.0")
+        .add_raw_manifest(b"[package]\nname = \"foo\"\nversion.workspace = true\n")
+        .build();
+
+    let response = token.publish_crate(PublishBuilder::new("foo", "1.0.0").tarball(tarball));
+    assert_eq!(response.status(), StatusCode::OK);
+    assert_eq!(
+        response.into_json(),
+        json!({ "errors": [{ "detail": "failed to parse `Cargo.toml` manifest file\n\nvalue from workspace hasn't been set" }] })
+    );
+}
+
+#[test]
+fn workspace_inheritance_with_dep() {
+    let (_app, _anon, _cookie, token) = TestApp::full().with_token();
+
+    let tarball = TarballBuilder::new("foo", "1.0.0")
+        .add_raw_manifest(
+            b"[package]\nname = \"foo\"\nversion = \"1.0.0\"\n\n[dependencies]\nserde.workspace = true\n",
+        )
+        .build();
+
+    let response = token.publish_crate(PublishBuilder::new("foo", "1.0.0").tarball(tarball));
+    assert_eq!(response.status(), StatusCode::OK);
+    assert_eq!(
+        response.into_json(),
+        json!({ "errors": [{ "detail": "failed to parse `Cargo.toml` manifest file\n\nvalue from workspace hasn't been set" }] })
     );
 }