diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index fa3b955..39b4750 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -118,6 +118,23 @@ jobs:
           fi
         env:
           RUFF_VERSION: ${{ steps.ruff-action.outputs.ruff-version }}
+  test-default-version-from-requirements:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Use default version from requirements.txt
+        id: ruff-action
+        uses: ./
+        with:
+          src: __tests__/fixtures/python-project
+          version-file: __tests__/fixtures/requirements.txt
+      - name: Correct version gets installed
+        run: |
+          if [ "$RUFF_VERSION" != "0.8.3" ]; then
+            exit 1
+          fi
+        env:
+          RUFF_VERSION: ${{ steps.ruff-action.outputs.ruff-version }}
   test-semver-range:
     runs-on: ubuntu-latest
     steps:
diff --git a/README.md b/README.md
index 371453b..f437a14 100644
--- a/README.md
+++ b/README.md
@@ -124,13 +124,13 @@ to install the latest version that satisfies the range.
 #### Install a version from a specified version file
 
 You can specify a file to read the version from.
-Currently `pyproject.toml` is supported.
+Currently `pyproject.toml` and `requirements.txt` are supported.
 
 ```yaml
 - name: Install a version from a specified version file
   uses: astral-sh/ruff-action@v3
   with:
-    version-file: "my-path/to/pyproject.toml"
+    version-file: "my-path/to/pyproject.toml-or-requirements.txt"
 ```
 
 ### Validate checksum
diff --git a/__tests__/fixtures/requirements.txt b/__tests__/fixtures/requirements.txt
new file mode 100644
index 0000000..c5721a8
--- /dev/null
+++ b/__tests__/fixtures/requirements.txt
@@ -0,0 +1 @@
+ruff==0.8.3
diff --git a/dist/ruff-action/index.js b/dist/ruff-action/index.js
index 866ad61..e19f6dd 100644
--- a/dist/ruff-action/index.js
+++ b/dist/ruff-action/index.js
@@ -30729,39 +30729,46 @@ exports.getRuffVersionFromPyproject = getRuffVersionFromPyproject;
 const fs = __importStar(__nccwpck_require__(3024));
 const core = __importStar(__nccwpck_require__(7484));
 const toml = __importStar(__nccwpck_require__(7106));
+function parseRequirements(allDependencies) {
+    const ruffVersionDefinition = allDependencies.find((dep) => dep.startsWith("ruff"));
+    if (ruffVersionDefinition) {
+        const ruffVersion = ruffVersionDefinition
+            .match(/^ruff([^A-Z0-9._-]+.*)$/)?.[1]
+            .trim();
+        if (ruffVersion?.startsWith("==")) {
+            return ruffVersion.slice(2);
+        }
+        core.info(`Found ruff version in pyproject.toml: ${ruffVersion}`);
+        return ruffVersion;
+    }
+    return undefined;
+}
+function parsePyproject(pyprojectContent) {
+    const pyproject = toml.parse(pyprojectContent);
+    const dependencies = pyproject?.project?.dependencies || [];
+    const optionalDependencies = Object.values(pyproject?.project?.["optional-dependencies"] || {}).flat();
+    const devDependencies = Object.values(pyproject?.["dependency-groups"] || {})
+        .flat()
+        .filter((item) => typeof item === "string");
+    return parseRequirements(dependencies.concat(optionalDependencies, devDependencies));
+}
 function getRuffVersionFromPyproject(filePath) {
     if (!fs.existsSync(filePath)) {
         core.warning(`Could not find file: ${filePath}`);
         return undefined;
     }
     const pyprojectContent = fs.readFileSync(filePath, "utf-8");
-    let pyproject;
+    if (filePath.endsWith(".txt")) {
+        return parseRequirements(pyprojectContent.split("\n"));
+    }
     try {
-        pyproject = toml.parse(pyprojectContent);
+        return parsePyproject(pyprojectContent);
     }
     catch (err) {
         const message = err.message;
         core.warning(`Error while parsing ${filePath}: ${message}`);
         return undefined;
     }
-    const dependencies = pyproject?.project?.dependencies || [];
-    const optionalDependencies = Object.values(pyproject?.project?.["optional-dependencies"] || {}).flat();
-    const devDependencies = Object.values(pyproject?.["dependency-groups"] || {})
-        .flat()
-        .filter((item) => typeof item === "string");
-    const allDependencies = dependencies.concat(optionalDependencies, devDependencies);
-    const ruffVersionDefinition = allDependencies.find((dep) => dep.startsWith("ruff"));
-    if (ruffVersionDefinition) {
-        const ruffVersion = ruffVersionDefinition
-            .match(/^ruff([^A-Z0-9._-]+.*)$/)?.[1]
-            .trim();
-        if (ruffVersion?.startsWith("==")) {
-            return ruffVersion.slice(2);
-        }
-        core.info(`Found ruff version in pyproject.toml: ${ruffVersion}`);
-        return ruffVersion;
-    }
-    return undefined;
 }
 
 
diff --git a/src/utils/pyproject.ts b/src/utils/pyproject.ts
index ec81eba..055ffc9 100644
--- a/src/utils/pyproject.ts
+++ b/src/utils/pyproject.ts
@@ -2,45 +2,7 @@ import * as fs from "node:fs";
 import * as core from "@actions/core";
 import * as toml from "smol-toml";
 
-export function getRuffVersionFromPyproject(
-  filePath: string,
-): string | undefined {
-  if (!fs.existsSync(filePath)) {
-    core.warning(`Could not find file: ${filePath}`);
-    return undefined;
-  }
-  const pyprojectContent = fs.readFileSync(filePath, "utf-8");
-  let pyproject:
-    | {
-        project?: {
-          dependencies?: string[];
-          "optional-dependencies"?: Map<string, string[]>;
-        };
-        "dependency-groups"?: Map<string, Array<string | object>>;
-      }
-    | undefined;
-  try {
-    pyproject = toml.parse(pyprojectContent);
-  } catch (err) {
-    const message = (err as Error).message;
-    core.warning(`Error while parsing ${filePath}: ${message}`);
-    return undefined;
-  }
-
-  const dependencies: string[] = pyproject?.project?.dependencies || [];
-  const optionalDependencies: string[] = Object.values(
-    pyproject?.project?.["optional-dependencies"] || {},
-  ).flat();
-  const devDependencies: string[] = Object.values(
-    pyproject?.["dependency-groups"] || {},
-  )
-    .flat()
-    .filter((item: string | object) => typeof item === "string");
-  const allDependencies: string[] = dependencies.concat(
-    optionalDependencies,
-    devDependencies,
-  );
-
+function parseRequirements(allDependencies: string[]): string | undefined {
   const ruffVersionDefinition = allDependencies.find((dep: string) =>
     dep.startsWith("ruff"),
   );
@@ -58,3 +20,45 @@ export function getRuffVersionFromPyproject(
 
   return undefined;
 }
+
+function parsePyproject(pyprojectContent: string): string | undefined {
+  const pyproject: {
+    project?: {
+      dependencies?: string[];
+      "optional-dependencies"?: Map<string, string[]>;
+    };
+    "dependency-groups"?: Map<string, Array<string | object>>;
+  } = toml.parse(pyprojectContent);
+  const dependencies: string[] = pyproject?.project?.dependencies || [];
+  const optionalDependencies: string[] = Object.values(
+    pyproject?.project?.["optional-dependencies"] || {},
+  ).flat();
+  const devDependencies: string[] = Object.values(
+    pyproject?.["dependency-groups"] || {},
+  )
+    .flat()
+    .filter((item: string | object) => typeof item === "string");
+  return parseRequirements(
+    dependencies.concat(optionalDependencies, devDependencies),
+  );
+}
+
+export function getRuffVersionFromPyproject(
+  filePath: string,
+): string | undefined {
+  if (!fs.existsSync(filePath)) {
+    core.warning(`Could not find file: ${filePath}`);
+    return undefined;
+  }
+  const pyprojectContent = fs.readFileSync(filePath, "utf-8");
+  if (filePath.endsWith(".txt")) {
+    return parseRequirements(pyprojectContent.split("\n"));
+  }
+  try {
+    return parsePyproject(pyprojectContent);
+  } catch (err) {
+    const message = (err as Error).message;
+    core.warning(`Error while parsing ${filePath}: ${message}`);
+    return undefined;
+  }
+}