diff --git a/colcon_cargo/package_identification/cargo_workspace.py b/colcon_cargo/package_identification/cargo_workspace.py
index 823dfe8..86499f3 100644
--- a/colcon_cargo/package_identification/cargo_workspace.py
+++ b/colcon_cargo/package_identification/cargo_workspace.py
@@ -50,6 +50,14 @@ def identify(self, metadata):  # noqa: D102
         )
         self.workspace_package_paths.update(ws_members)
 
+        workspace_metadata = content['workspace'].get('metadata', {})
+        colcon_metadata = workspace_metadata.get('colcon', {})
+        self.workspace_package_paths.update(
+            member
+            for pattern in colcon_metadata.get('additional-packages', ())
+            for member in metadata.path.glob(pattern)
+        )
+
         if 'package' not in content:
             # Prevent any further attempts to discover packages in this
             # directory and let the workspace dictate where to look for
diff --git a/test/rust-workspace/Cargo.toml b/test/rust-workspace/Cargo.toml
index 2226f44..cf07f98 100644
--- a/test/rust-workspace/Cargo.toml
+++ b/test/rust-workspace/Cargo.toml
@@ -7,3 +7,6 @@ edition = "2018"
 [workspace]
 members = ["workspace-mem*"]
 default-members = ["workspace-mem*"]
+
+[workspace.metadata.colcon]
+additional-packages = ["additional-pack*"]
diff --git a/test/rust-workspace/additional-package/Cargo.toml b/test/rust-workspace/additional-package/Cargo.toml
new file mode 100644
index 0000000..f3ad2cc
--- /dev/null
+++ b/test/rust-workspace/additional-package/Cargo.toml
@@ -0,0 +1,5 @@
+[package]
+name = "additional-package"
+version = "0.1.0"
+authors = ["Test<test@test.com>"]
+edition = "2018"
diff --git a/test/rust-workspace/additional-package/src/lib.rs b/test/rust-workspace/additional-package/src/lib.rs
new file mode 100644
index 0000000..e69de29
diff --git a/test/rust-workspace/additional-package/src/main.rs b/test/rust-workspace/additional-package/src/main.rs
new file mode 100644
index 0000000..e7a11a9
--- /dev/null
+++ b/test/rust-workspace/additional-package/src/main.rs
@@ -0,0 +1,3 @@
+fn main() {
+    println!("Hello, world!");
+}
diff --git a/test/test_build.py b/test/test_build.py
index 6521cd7..163c525 100644
--- a/test/test_build.py
+++ b/test/test_build.py
@@ -98,10 +98,14 @@ def test_package_discovery():
             cpi.PRIORITY: {'cargo': cpi},
         })
 
-    assert len(descs) == 1
+    assert len(descs) == 2
+    descs = sorted(descs, key=lambda d: d.name)
     desc = descs.pop()
     assert desc.type == 'cargo'
     assert desc.name == 'workspace-member'
+    desc = descs.pop()
+    assert desc.type == 'cargo'
+    assert desc.name == 'additional-package'
 
 
 # Ported from Python 3.13 implementation