diff --git a/action.yaml b/action.yaml
index 6ae018c..f6a80b4 100644
--- a/action.yaml
+++ b/action.yaml
@@ -8,11 +8,11 @@ inputs:
   pypi-base-url:
     description: "The PyPI registry URL"
     required: true
-  override-version:
-    description: "Don't check GitHub for the latest version, use this one"
-    required: false
   github-repository:
-    description: "The package's GitHub repository name (owner/repo). Required if override-version is unset"
+    description: "The package's GitHub repository name (owner/repo)"
+    required: true
+  unstable-branch:
+    description: "Whether to get a version representing the latest commit on this branch"
     required: false
 
 outputs:
@@ -32,5 +32,5 @@ runs:
         REPOSITORY: ${{ inputs.github-repository }}
         PACKAGE: ${{ inputs.pypi-package }}
         BASE_URL: ${{ inputs.pypi-base-url }}
-        VERSION: ${{ inputs.override-version }}
+        BRANCH: ${{ inputs.unstable-branch }}
 
diff --git a/check.py b/check.py
index e4b51db..66446b7 100644
--- a/check.py
+++ b/check.py
@@ -5,14 +5,39 @@ import re
 import sys
 import requests
 
+from datetime import datetime
 
-def get_github_version(repository: str) -> str: 
+
+def get_release_version(repository: str) -> str: 
     try:
         return requests.get(f"https://api.github.com/repos/{repository}/releases/latest").json()["tag_name"].removeprefix("v")
     except Exception:
         return requests.get(f"https://api.github.com/repos/{repository}/tags").json()[0]["name"].removeprefix("v")
 
 
+def get_unstable_version(repository: str, branch: str) -> str:
+    base_url = f"https://api.github.com/repos/{repository}/commits?sha={branch}"
+
+    latest_commit = requests.get(f"{base_url}&per_page=1").json()[0]
+    commit_date = datetime.strptime(latest_commit["commit"]["committer"]["date"], "%Y-%m-%dT%H:%M:%SZ")
+
+    since_iso = commit_date.replace(hour=0, minute=0, second=0, microsecond=0).isoformat().replace("+00:00", "Z")
+    
+    commit_count = 0
+    page = 1
+    
+    while True:
+        commits = requests.get(f"{base_url}&since={since_iso}&per_page=100&page={page}").json()
+        commit_count += len(commits)
+
+        if len(commits) < 100:
+            break
+        
+        page += 1
+
+    return f"{branch}.{commit_date.strftime("%Y%m%d")}.dev{commit_count}"
+
+
 def does_pypi_version_exist(base_url: str, package: str, version: str) -> bool:
     base_url = base_url.removesuffix("/")
     version = version.replace(".", "\\.")
@@ -24,11 +49,9 @@ def does_pypi_version_exist(base_url: str, package: str, version: str) -> bool:
 def main():
     package = os.environ["PACKAGE"]
     base_url = os.environ["BASE_URL"]
+    repository = os.environ["REPOSITORY"]
 
-    version = os.environ.get(
-        "VERSION",
-        get_github_version(os.environ["REPOSITORY"])
-    )
+    version = get_release_version(repository) if not os.environ.get("BRANCH", False) else get_unstable_version(repository, os.environ["BRANCH"]) 
     
     if does_pypi_version_exist(base_url, package, version):
         sys.exit(0)