diff --git a/crates/uv-resolver/src/lock/export/pylock_toml.rs b/crates/uv-resolver/src/lock/export/pylock_toml.rs
index a27440c2c..70d87c9d1 100644
--- a/crates/uv-resolver/src/lock/export/pylock_toml.rs
+++ b/crates/uv-resolver/src/lock/export/pylock_toml.rs
@@ -37,7 +37,27 @@ use crate::{Installable, LockError, RequiresPython};
 
 #[derive(Debug, thiserror::Error)]
 pub enum PylockTomlError {
-    #[error("`packages` entry for `{0}` must contain one of: `wheels`, `directory`, `archive`, `sdist`, or `vcs`")]
+    #[error("Package `{0}` includes both a registry (`packages.wheels`) and a directory source (`packages.directory`)")]
+    WheelWithDirectory(PackageName),
+    #[error("Package `{0}` includes both a registry (`packages.wheels`) and a VCS source (`packages.vcs`)")]
+    WheelWithVcs(PackageName),
+    #[error("Package `{0}` includes both a registry (`packages.wheels`) and an archive source (`packages.archive`)")]
+    WheelWithArchive(PackageName),
+    #[error("Package `{0}` includes both a registry (`packages.sdist`) and a directory source (`packages.directory`)")]
+    SdistWithDirectory(PackageName),
+    #[error("Package `{0}` includes both a registry (`packages.sdist`) and a VCS source (`packages.vcs`)")]
+    SdistWithVcs(PackageName),
+    #[error("Package `{0}` includes both a registry (`packages.sdist`) and an archive source (`packages.archive`)")]
+    SdistWithArchive(PackageName),
+    #[error("Package `{0}` includes both a directory (`packages.directory`) and a VCS source (`packages.vcs`)")]
+    DirectoryWithVcs(PackageName),
+    #[error("Package `{0}` includes both a directory (`packages.directory`) and an archive source (`packages.archive`)")]
+    DirectoryWithArchive(PackageName),
+    #[error("Package `{0}` includes both a VCS (`packages.vcs`) and an archive source (`packages.archive`)")]
+    VcsWithArchive(PackageName),
+    #[error(
+        "Package `{0}` must include one of: `wheels`, `directory`, `archive`, `sdist`, or `vcs`"
+    )]
     MissingSource(PackageName),
     #[error("`packages.wheel` entry for `{0}` must have a `path` or `url`")]
     WheelMissingPathUrl(PackageName),
@@ -558,6 +578,47 @@ impl<'lock> PylockToml {
         let root = graph.add_node(Node::Root);
 
         for package in self.packages {
+            match (
+                package.wheels.is_some(),
+                package.sdist.is_some(),
+                package.directory.is_some(),
+                package.vcs.is_some(),
+                package.archive.is_some(),
+            ) {
+                // `packages.wheels` is mutually exclusive with `packages.directory`, `packages.vcs`, and `packages.archive`.
+                (true, _, true, _, _) => {
+                    return Err(PylockTomlError::WheelWithDirectory(package.name.clone()));
+                }
+                (true, _, _, true, _) => {
+                    return Err(PylockTomlError::WheelWithVcs(package.name.clone()));
+                }
+                (true, _, _, _, true) => {
+                    return Err(PylockTomlError::WheelWithArchive(package.name.clone()));
+                }
+                // `packages.sdist` is mutually exclusive with `packages.directory`, `packages.vcs`, and `packages.archive`.
+                (_, true, true, _, _) => {
+                    return Err(PylockTomlError::SdistWithDirectory(package.name.clone()));
+                }
+                (_, true, _, true, _) => {
+                    return Err(PylockTomlError::SdistWithVcs(package.name.clone()));
+                }
+                (_, true, _, _, true) => {
+                    return Err(PylockTomlError::SdistWithArchive(package.name.clone()));
+                }
+                // `packages.directory` is mutually exclusive with `packages.vcs`, and `packages.archive`.
+                (_, _, true, true, _) => {
+                    return Err(PylockTomlError::DirectoryWithVcs(package.name.clone()));
+                }
+                (_, _, true, _, true) => {
+                    return Err(PylockTomlError::DirectoryWithArchive(package.name.clone()));
+                }
+                // `packages.vcs` is mutually exclusive with `packages.archive`.
+                (_, _, _, true, true) => {
+                    return Err(PylockTomlError::VcsWithArchive(package.name.clone()));
+                }
+                _ => {}
+            }
+
             // Omit packages that aren't relevant to the current environment.
             let install = package.marker.evaluate(markers, &[]);
 
diff --git a/crates/uv/tests/it/pip_install.rs b/crates/uv/tests/it/pip_install.rs
index ae2c9b96b..2682385a7 100644
--- a/crates/uv/tests/it/pip_install.rs
+++ b/crates/uv/tests/it/pip_install.rs
@@ -11071,3 +11071,40 @@ fn pep_751_mix() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn pep_751_multiple_sources() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let pylock_toml = context.temp_dir.child("pylock.toml");
+    pylock_toml.write_str(r#"
+        # This file was autogenerated by uv via the following command:
+        #    uv export --cache-dir [CACHE_DIR] -o pylock.toml
+        lock-version = "1.0"
+        created-by = "uv"
+        requires-python = ">=3.12"
+
+        [[packages]]
+        name = "typing-extensions"
+        version = "4.10.0"
+        index = "https://pypi.org/simple"
+        sdist = { url = "https://files.pythonhosted.org/packages/16/3a/0d26ce356c7465a19c9ea8814b960f8a36c3b0d07c323176620b7b483e44/typing_extensions-4.10.0.tar.gz", size = 77558, hashes = { sha256 = "b0abd7c89e8fb96f98db18d86106ff1d90ab692004eb746cf6eda2682f91b3cb" } }
+        wheels = [{ url = "https://files.pythonhosted.org/packages/f9/de/dc04a3ea60b22624b51c703a84bbe0184abcd1d0b9bc8074b5d6b7ab90bb/typing_extensions-4.10.0-py3-none-any.whl", size = 33926, hashes = { sha256 = "69b1a937c3a517342112fb4c6df7e72fc39a38e7891a5730ed4985b5214b5475" } }]
+        archive = { path = "iniconfig-2.0.0-py3-none-any.whl", hashes = { sha256 = "c5185871a79d2e3b22d2d1b94ac2824226a63c6b741c88f7ae975f18b6778374" } }
+    "#)?;
+
+    uv_snapshot!(context.filters(), context.pip_install()
+        .arg("--preview")
+        .arg("-r")
+        .arg("pylock.toml"), @r"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Package `typing-extensions` includes both a registry (`packages.wheels`) and an archive source (`packages.archive`)
+    "
+    );
+
+    Ok(())
+}