diff --git a/PyTeX b/PyTeX
index e213c70..dbdd99c 160000
--- a/PyTeX
+++ b/PyTeX
@@ -1 +1 @@
-Subproject commit e213c706eaaad4b3728c52b5a47d9f6d602ddb0e
+Subproject commit dbdd99cc3d6e02b0cfadb1d337f6b85c5f52a9b5
diff --git a/build.py b/build.py
index 44321fe..204c941 100644
--- a/build.py
+++ b/build.py
@@ -1,18 +1,53 @@
 from pathlib import *
 import sys
+import git
+from datetime import *
 sys.path.insert(0, 'PyTeX/')
 
 from package_formatter import PackageFormatter
 from replacements import make_default_commands
+from git_version import git_describe
+
+BUILD_DETAILS = [
+    "Build details:",
+    "  Build time: {build_time}",
+    "  PyTeX version: {pytex_version} (commit {pytex_commit_hash})",
+    "  LatexPackages version: {packages_version} (commit {packages_commit_hash})"
+]
+
+
+def build_details():
+    repo = git.Repo()
+    repo_description = git_describe(repo.head.ref.commit)
+    pytex_repo = repo.submodule('PyTeX').module()
+    pytex_repo_description = git_describe(pytex_repo.head.ref.commit)
+    return list(map(lambda line: line.format(
+            build_time=datetime.now().strftime('%Y/%m/%d %H:%M'),
+            pytex_version=pytex_repo_description,
+            pytex_commit_hash=pytex_repo.head.ref.commit.hexsha[0:7],
+            packages_version=repo_description,
+            packages_commit_hash=repo.head.ref.commit.hexsha[0:7]
+            ),BUILD_DETAILS))
+
 
 def build(build_dir: str):
     input_root = Path('./packages').resolve()
     output = input_root / build_dir
+    print('[PyTeX] Getting git repository information...')
+    extra_header = build_details()
+    print('[PyTeX] ..done.')
+    if git.Repo().is_dirty():
+        extra_header += ['WARNING: Local changes to git repository detected.',
+                '         The build will not be reproducible (!)']
+    num_files = 0
     for file in input_root.rglob('*.pysty'):
-        formatter = PackageFormatter(package_name=file.with_suffix('').name)
+        num_files+=1
+        formatter = PackageFormatter(package_name=file.with_suffix('').name, extra_header=extra_header)
         print('[PyTeX] Writing file {}'.format(formatter.file_name))
         make_default_commands(formatter)
         formatter.format_package(file, Path('./').resolve() / build_dir / str(file.parent.relative_to(input_root)))
+    print(f'[PyTeX] Successfully built {num_files} packages in {build_dir}/')
 
 if __name__ == "__main__":
     build('build')
+
diff --git a/git_version.py b/git_version.py
new file mode 100644
index 0000000..11009de
--- /dev/null
+++ b/git_version.py
@@ -0,0 +1,45 @@
+import git
+from typing import Dict
+
+
+def get_history(commit: git.objects.commit.Commit, priority=0, depth=0) -> Dict:
+    commit_history = {commit.hexsha: {
+        'priority': priority,
+        'depth': depth
+    }}
+    if len(commit.parents) == 0:
+        return commit_history
+    else:
+        commit_history.update(get_history(commit.parents[0], priority, depth+1))
+        for parent in commit.parents[1:]:
+            commit_history.update(get_history(parent, priority+1, depth+1))
+        return commit_history
+
+
+def git_describe(commit: git.objects.commit.Commit):
+    commit_history = get_history(commit)
+    latest_tag = None
+    for tag in commit.repo.tags:
+        sha = tag.commit.hexsha
+        if sha in commit_history.keys():
+            if latest_tag is None:
+                latest_tag = tag
+            elif commit_history[sha]['priority'] < commit_history[latest_tag.commit.hexsha]['priority']:
+                latest_tag = tag
+            elif commit_history[sha]['priority'] > commit_history[latest_tag.commit.hexsha]['priority']:
+                pass  # move on
+            elif commit_history[sha]['depth'] < commit_history[latest_tag.commit.hexsha]['depth']:
+                latest_tag = tag
+            elif commit_history[sha]['depth'] > commit_history[latest_tag.commit.hexsha]['depth']:
+                pass  # move on
+            elif tag.object.tagged_date > latest_tag.object.tagged_date:
+                latest_tag = tag
+    if latest_tag is None:
+        return "No tags found - cannot describe anything."
+    else:
+        msg = latest_tag.name
+        if commit_history[latest_tag.commit.hexsha]['depth'] != 0:
+            msg += "-{depth}".format(depth=commit_history[latest_tag.commit.hexsha]['depth'])
+        if commit.repo.is_dirty(untracked_files=True):
+            msg += '-*'
+        return msg