diff --git a/README.md b/README.md
index 9ece287..21b4ebd 100644
--- a/README.md
+++ b/README.md
@@ -147,7 +147,7 @@ This cache is automatically keyed by:
   available),
 - the following values, if `add-rust-environment-hash-key` is `"true"`:
   - the value of some compiler-specific environment variables (eg. RUSTFLAGS, etc), and
-  - a hash of all `Cargo.lock` / `Cargo.toml` files found anywhere in the repository (if present).
+  - a hash of the workspace's `Cargo.lock` and of the `Cargo.toml` of the workspace root and every workspace member (if present).
   - a hash of all `rust-toolchain` / `rust-toolchain.toml` files in the root of the repository (if present).
   - a hash of all `.cargo/config.toml` files in the root of the repository (if present).
 
diff --git a/dist/cache-BzPKClMA.js b/dist/cache-BaeW9gVW.js
similarity index 99%
rename from dist/cache-BzPKClMA.js
rename to dist/cache-BaeW9gVW.js
index 9c7a3dc..98c32e1 100644
--- a/dist/cache-BzPKClMA.js
+++ b/dist/cache-BaeW9gVW.js
@@ -1,4 +1,4 @@
-import { x as commonjsGlobal, y as requireTunnel, z as getDefaultExportFromCjs, A as getAugmentedNamespace } from './cleanup-e3M0pm4f.js';
+import { x as commonjsGlobal, y as requireTunnel, z as getDefaultExportFromCjs, A as getAugmentedNamespace } from './cleanup-DYJDrBaf.js';
 import os__default from 'os';
 import crypto__default from 'crypto';
 import fs__default from 'fs';
diff --git a/dist/cache-Dl81DHPs.js b/dist/cache-DoD2J4WY.js
similarity index 99%
rename from dist/cache-Dl81DHPs.js
rename to dist/cache-DoD2J4WY.js
index f7efb8f..d2f1532 100644
--- a/dist/cache-Dl81DHPs.js
+++ b/dist/cache-DoD2J4WY.js
@@ -1,4 +1,4 @@
-import { f as debug, m as mkdirP, n as create, l as exec, w as which, o as warning, i as info, H as HttpCodes, p as HttpClientError, q as HttpClient, t as isDebug, u as setSecret, B as BearerCredentialHandler, v as rmRF, e as error } from './cleanup-e3M0pm4f.js';
+import { f as debug, m as mkdirP, n as create, l as exec, w as which, o as warning, i as info, H as HttpCodes, p as HttpClientError, q as HttpClient, t as isDebug, u as setSecret, B as BearerCredentialHandler, v as rmRF, e as error } from './cleanup-DYJDrBaf.js';
 import * as path from 'path';
 import * as crypto from 'crypto';
 import * as fs from 'fs';
diff --git a/dist/cleanup-e3M0pm4f.js b/dist/cleanup-DYJDrBaf.js
similarity index 99%
rename from dist/cleanup-e3M0pm4f.js
rename to dist/cleanup-DYJDrBaf.js
index d7406fd..486168f 100644
--- a/dist/cleanup-e3M0pm4f.js
+++ b/dist/cleanup-DYJDrBaf.js
@@ -34972,10 +34972,10 @@ async function getCacheProvider() {
     let cache;
     switch (cacheProvider) {
         case "github":
-            cache = await import('./cache-Dl81DHPs.js');
+            cache = await import('./cache-DoD2J4WY.js');
             break;
         case "warpbuild":
-            cache = await import('./cache-BzPKClMA.js').then(function (n) { return n.c; });
+            cache = await import('./cache-BaeW9gVW.js').then(function (n) { return n.c; });
             break;
         default:
             throw new Error(`The \`cache-provider\` \`${cacheProvider}\` is not valid.`);
@@ -35006,6 +35006,7 @@ class Workspace {
     async getPackages(cmdFormat, filter, extraArgs) {
         const cmd = "cargo metadata --all-features --format-version 1" + (extraArgs ? ` ${extraArgs}` : "");
         let packages = [];
+        let workspaceRoot = this.root;
         try {
             debug(`collecting metadata for "${this.root}"`);
             const meta = JSON.parse(await getCmdOutput(cmdFormat, cmd, {
@@ -35013,6 +35014,7 @@ class Workspace {
                 env: { ...process.env, CARGO_ENCODED_RUSTFLAGS: "" },
             }));
             debug(`workspace "${this.root}" has ${meta.packages.length} packages`);
+            workspaceRoot = meta.workspace_root;
             for (const pkg of meta.packages.filter(filter)) {
                 const targets = pkg.targets.filter((t) => t.kind.some((kind) => SAVE_TARGETS.has(kind))).map((t) => t.name);
                 packages.push({ name: pkg.name, version: pkg.version, targets, path: path__default.dirname(pkg.manifest_path) });
@@ -35021,13 +35023,16 @@ class Workspace {
         catch (err) {
             console.error(err);
         }
-        return packages;
+        return { packages, workspaceRoot };
     }
     async getPackagesOutsideWorkspaceRoot(cmdFormat) {
-        return await this.getPackages(cmdFormat, (pkg) => !pkg.manifest_path.startsWith(this.root));
+        const filter = (pkg) => !pkg.manifest_path.startsWith(this.root);
+        return (await this.getPackages(cmdFormat, filter)).packages;
     }
+    /** The workspace's members, and the root directory of the cargo workspace they belong to. */
     async getWorkspaceMembers(cmdFormat) {
-        return await this.getPackages(cmdFormat, (_) => true, "--no-deps");
+        const { packages, workspaceRoot } = await this.getPackages(cmdFormat, (_) => true, "--no-deps");
+        return { members: packages, workspaceRoot };
     }
 }
 
@@ -35155,9 +35160,15 @@ class CacheConfig {
             for (const workspace of workspaces) {
                 const root = workspace.root;
                 keyFiles.push(...(await globFiles(`${root}/**/.cargo/config.toml\n${root}/**/rust-toolchain\n${root}/**/rust-toolchain.toml`)));
-                const workspaceMembers = await workspace.getWorkspaceMembers(cmdFormat);
-                const cargo_manifests = sort_and_uniq(workspaceMembers.map((member) => path__default.join(member.path, "Cargo.toml")));
-                for (const cargo_manifest of cargo_manifests) {
+                const { members, workspaceRoot } = await workspace.getWorkspaceMembers(cmdFormat);
+                const cargo_manifests = members.map((member) => path__default.join(member.path, "Cargo.toml"));
+                // A virtual workspace's root manifest belongs to no member, yet its `[profile]` and `[patch]`
+                // sections apply to every member.
+                const root_manifest = path__default.join(workspaceRoot, "Cargo.toml");
+                if (await exists(root_manifest)) {
+                    cargo_manifests.push(root_manifest);
+                }
+                for (const cargo_manifest of sort_and_uniq(cargo_manifests)) {
                     try {
                         const content = await fs$1.readFile(cargo_manifest, { encoding: "utf8" });
                         // Use any since TomlPrimitive is not exposed
@@ -35168,12 +35179,16 @@ class CacheConfig {
                                 pack["version"] = "0.0.0";
                             }
                         }
-                        for (const prefix of ["", "build-", "dev-"]) {
-                            const section_name = `${prefix}dependencies`;
-                            if (!(section_name in parsed)) {
+                        const workspace_table = parsed.workspace ?? {};
+                        if ("package" in workspace_table && "version" in workspace_table.package) {
+                            workspace_table.package["version"] = "0.0.0";
+                        }
+                        const dependency_tables = ["", "build-", "dev-"].map((prefix) => parsed[`${prefix}dependencies`]);
+                        dependency_tables.push(workspace_table.dependencies);
+                        for (const deps of dependency_tables) {
+                            if (deps === undefined) {
                                 continue;
                             }
-                            const deps = parsed[section_name];
                             for (const key of Object.keys(deps)) {
                                 const dep = deps[key];
                                 try {
@@ -35198,7 +35213,7 @@ class CacheConfig {
                         keyFiles.push(cargo_manifest);
                     }
                 }
-                const cargo_lock = path__default.join(workspace.root, "Cargo.lock");
+                const cargo_lock = path__default.join(workspaceRoot, "Cargo.lock");
                 if (await exists(cargo_lock)) {
                     try {
                         const content = await fs$1.readFile(cargo_lock, { encoding: "utf8" });
diff --git a/dist/restore.js b/dist/restore.js
index fe64211..5a77ed8 100644
--- a/dist/restore.js
+++ b/dist/restore.js
@@ -1,4 +1,4 @@
-import { e as error, g as getCacheProvider, a as getInput, b as exportVariable, C as CacheConfig, i as info, c as cleanTargetDir, r as reportError, s as setOutput } from './cleanup-e3M0pm4f.js';
+import { e as error, g as getCacheProvider, a as getInput, b as exportVariable, C as CacheConfig, i as info, c as cleanTargetDir, r as reportError, s as setOutput } from './cleanup-DYJDrBaf.js';
 import 'os';
 import 'crypto';
 import 'fs';
diff --git a/dist/save.js b/dist/save.js
index 3a8c8e5..fcebd7d 100644
--- a/dist/save.js
+++ b/dist/save.js
@@ -1,4 +1,4 @@
-import { e as error, g as getCacheProvider, a as getInput, d as isCacheUpToDate, i as info, C as CacheConfig, c as cleanTargetDir, f as debug, h as cleanRegistry, j as cleanBin, k as cleanGit, r as reportError, l as exec } from './cleanup-e3M0pm4f.js';
+import { e as error, g as getCacheProvider, a as getInput, d as isCacheUpToDate, i as info, C as CacheConfig, c as cleanTargetDir, f as debug, h as cleanRegistry, j as cleanBin, k as cleanGit, r as reportError, l as exec } from './cleanup-DYJDrBaf.js';
 import 'os';
 import 'crypto';
 import 'fs';
@@ -63,8 +63,8 @@ async function run() {
         for (const workspace of config.workspaces) {
             const packages = await workspace.getPackagesOutsideWorkspaceRoot(config.cmdFormat);
             if (workspaceCrates === "true") {
-                const wsMembers = await workspace.getWorkspaceMembers(config.cmdFormat);
-                packages.push(...wsMembers);
+                const { members } = await workspace.getWorkspaceMembers(config.cmdFormat);
+                packages.push(...members);
             }
             allPackages.push(...packages);
             try {
diff --git a/src/config.ts b/src/config.ts
index 67633b9..78499d4 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -167,11 +167,17 @@ export class CacheConfig {
           )),
         );
 
-        const workspaceMembers = await workspace.getWorkspaceMembers(cmdFormat);
+        const { members, workspaceRoot } = await workspace.getWorkspaceMembers(cmdFormat);
 
-        const cargo_manifests = sort_and_uniq(workspaceMembers.map((member) => path.join(member.path, "Cargo.toml")));
+        const cargo_manifests = members.map((member) => path.join(member.path, "Cargo.toml"));
+        // A virtual workspace's root manifest belongs to no member, yet its `[profile]` and `[patch]`
+        // sections apply to every member.
+        const root_manifest = path.join(workspaceRoot, "Cargo.toml");
+        if (await exists(root_manifest)) {
+          cargo_manifests.push(root_manifest);
+        }
 
-        for (const cargo_manifest of cargo_manifests) {
+        for (const cargo_manifest of sort_and_uniq(cargo_manifests)) {
           try {
             const content = await fs.readFile(cargo_manifest, { encoding: "utf8" });
             // Use any since TomlPrimitive is not exposed
@@ -184,12 +190,17 @@ export class CacheConfig {
               }
             }
 
-            for (const prefix of ["", "build-", "dev-"]) {
-              const section_name = `${prefix}dependencies`;
-              if (!(section_name in parsed)) {
+            const workspace_table = parsed.workspace ?? {};
+            if ("package" in workspace_table && "version" in workspace_table.package) {
+              workspace_table.package["version"] = "0.0.0";
+            }
+
+            const dependency_tables = ["", "build-", "dev-"].map((prefix) => parsed[`${prefix}dependencies`]);
+            dependency_tables.push(workspace_table.dependencies);
+            for (const deps of dependency_tables) {
+              if (deps === undefined) {
                 continue;
               }
-              const deps = parsed[section_name];
 
               for (const key of Object.keys(deps)) {
                 const dep = deps[key];
@@ -217,7 +228,7 @@ export class CacheConfig {
           }
         }
 
-        const cargo_lock = path.join(workspace.root, "Cargo.lock");
+        const cargo_lock = path.join(workspaceRoot, "Cargo.lock");
         if (await exists(cargo_lock)) {
           try {
             const content = await fs.readFile(cargo_lock, { encoding: "utf8" });
diff --git a/src/save.ts b/src/save.ts
index 4d4cdc3..dae4a27 100644
--- a/src/save.ts
+++ b/src/save.ts
@@ -41,8 +41,8 @@ async function run() {
     for (const workspace of config.workspaces) {
       const packages = await workspace.getPackagesOutsideWorkspaceRoot(config.cmdFormat);
       if (workspaceCrates === "true") {
-        const wsMembers = await workspace.getWorkspaceMembers(config.cmdFormat);
-        packages.push(...wsMembers);
+        const { members } = await workspace.getWorkspaceMembers(config.cmdFormat);
+        packages.push(...members);
       }
       allPackages.push(...packages);
       try {
diff --git a/src/workspace.ts b/src/workspace.ts
index 434957d..8216d36 100644
--- a/src/workspace.ts
+++ b/src/workspace.ts
@@ -15,9 +15,10 @@ export class Workspace {
     cmdFormat: string,
     filter: (p: Meta["packages"][0]) => boolean,
     extraArgs?: string,
-  ): Promise<Packages> {
+  ): Promise<{ packages: Packages; workspaceRoot: string }> {
     const cmd = "cargo metadata --all-features --format-version 1" + (extraArgs ? ` ${extraArgs}` : "");
     let packages: Packages = [];
+    let workspaceRoot = this.root;
     try {
       core.debug(`collecting metadata for "${this.root}"`);
       const meta: Meta = JSON.parse(
@@ -27,6 +28,7 @@ export class Workspace {
         }),
       );
       core.debug(`workspace "${this.root}" has ${meta.packages.length} packages`);
+      workspaceRoot = meta.workspace_root;
       for (const pkg of meta.packages.filter(filter)) {
         const targets = pkg.targets.filter((t) => t.kind.some((kind) => SAVE_TARGETS.has(kind))).map((t) => t.name);
         packages.push({ name: pkg.name, version: pkg.version, targets, path: path.dirname(pkg.manifest_path) });
@@ -34,15 +36,18 @@ export class Workspace {
     } catch (err) {
       console.error(err);
     }
-    return packages;
+    return { packages, workspaceRoot };
   }
 
   public async getPackagesOutsideWorkspaceRoot(cmdFormat: string): Promise<Packages> {
-    return await this.getPackages(cmdFormat, (pkg) => !pkg.manifest_path.startsWith(this.root));
+    const filter = (pkg: Meta["packages"][0]) => !pkg.manifest_path.startsWith(this.root);
+    return (await this.getPackages(cmdFormat, filter)).packages;
   }
 
-  public async getWorkspaceMembers(cmdFormat: string): Promise<Packages> {
-    return await this.getPackages(cmdFormat, (_) => true, "--no-deps");
+  /** The workspace's members, and the root directory of the cargo workspace they belong to. */
+  public async getWorkspaceMembers(cmdFormat: string): Promise<{ members: Packages; workspaceRoot: string }> {
+    const { packages, workspaceRoot } = await this.getPackages(cmdFormat, (_) => true, "--no-deps");
+    return { members: packages, workspaceRoot };
   }
 }
 
@@ -56,6 +61,7 @@ export interface PackageDefinition {
 export type Packages = Array<PackageDefinition>;
 
 interface Meta {
+  workspace_root: string;
   packages: Array<{
     name: string;
     version: string;