diff --git a/rust2rpm/__main__.py b/rust2rpm/__main__.py
index 2bb25cb..f258e29 100644
--- a/rust2rpm/__main__.py
+++ b/rust2rpm/__main__.py
@@ -15,29 +15,18 @@ import shutil
 import sys
 import tarfile
 import tempfile
-import time
 import subprocess
 
-import jinja2
 import requests
 import tqdm
 
-from . import Metadata, licensing, __version__
-from .metadata import normalize_deps
+from . import Metadata, licensing, generator
 
 DEFAULT_EDITOR = "vi"
 XDG_CACHE_HOME = os.getenv("XDG_CACHE_HOME", os.path.expanduser("~/.cache"))
 CACHEDIR = os.path.join(XDG_CACHE_HOME, "rust2rpm")
 API_URL = "https://crates.io/api/v1/"
 DIST_GIT_URL = "https://src.fedoraproject.org/api/0/"
-JINJA_ENV = jinja2.Environment(
-    loader=jinja2.ChoiceLoader([
-        jinja2.FileSystemLoader(["/"]),
-        jinja2.PackageLoader("rust2rpm", "templates"),
-    ]),
-    extensions=["jinja2.ext.do"],
-    trim_blocks=True,
-    lstrip_blocks=True)
 LICENSES = re.compile(r"""
          COPYING(?:[.-].*)?|COPYRIGHT(?:[.-].*)?|
          EULA(?:[.-].*)?|[Ll]icen[cs]e|[Ll]icen[cs]e.*|
@@ -333,10 +322,6 @@ def make_diff_metadata(args, crate, version):
         shutil.copy2(cratef, os.path.join(os.getcwd(), f"{metadata.name}-{version}.crate"))
     return crate, diff, metadata, doc_files, license_files
 
-def to_list(s):
-    if not s:
-        return []
-    return list(filter(None, (l.strip() for l in s.splitlines())))
 
 def detect_rpmautospec(default_target, spec_file):
     """Guess whether %autorelease+%autochangelog should be used
@@ -486,34 +471,9 @@ def main():
 
     crate, diff, metadata, doc_files, license_files = make_diff_metadata(args, args.crate, args.version)
 
-    JINJA_ENV.globals["normalize_deps"] = normalize_deps
-    JINJA_ENV.globals["to_list"] = to_list
-    template = JINJA_ENV.get_template("main.spec")
+    patch_file = f"{metadata.name}-fix-metadata.diff" if diff else None
 
-    if args.patch and len(diff) > 0:
-        patch_file = f"{metadata.name}-fix-metadata.diff"
-    else:
-        patch_file = None
-
-    kwargs = {}
-    kwargs["generator_version"] = __version__
-    kwargs["crate"] = crate
-    kwargs["target"] = args.target
-
-    bins = [tgt for tgt in metadata.targets if tgt.kind == "bin"]
-    libs = [tgt for tgt in metadata.targets if tgt.kind in {"lib", "rlib", "proc-macro"}]
-    is_bin = len(bins) > 0
-    is_lib = len(libs) > 0
-    if is_bin:
-        kwargs["include_main"] = True
-        kwargs["bins"] = bins
-    elif is_lib:
-        kwargs["include_main"] = False
-    else:
-        raise ValueError("No bins and no libs")
-    kwargs["include_devel"] = is_lib
-
-    kwargs["pkg_name"] = pkg_name = package_name_suffixed(metadata.name, args.suffix)
+    pkg_name = package_name_suffixed(metadata.name, args.suffix)
     spec_file = pathlib.Path(f"{pkg_name}.spec")
 
     if args.target in {"fedora"} and args.existence_check and not os.path.exists(spec_file):
@@ -524,58 +484,13 @@ def main():
             print("Re-run with --no-existence-check if you still want to convert it.")
             sys.exit(1)
 
-    kwargs["auto_changelog_entry"] = args.auto_changelog_entry
-
-    rpmautospec = args.rpmautospec
-    if rpmautospec is None:
-        rpmautospec = detect_rpmautospec(args.target, spec_file)
-    kwargs["rpmautospec"] = rpmautospec
-
-    kwargs["relative_license_paths"] = args.relative_license_paths
-
-    if args.target in {"fedora", "mageia", "opensuse"}:
-        kwargs["include_build_requires"] = True
-        kwargs["include_provides"] = False
-        kwargs["include_requires"] = False
-    elif args.target == "plain":
-        kwargs["include_build_requires"] = True
-        kwargs["include_provides"] = True
-        kwargs["include_requires"] = True
-    else:
-        assert False, f"Unknown target {args.target!r}"
-
-    if args.target == "mageia":
-        kwargs["pkg_release"] = "%mkrel 1"
-        kwargs["rust_group"] = "Development/Rust"
-    elif args.target == "opensuse":
-        kwargs["spec_copyright_year"] = time.strftime("%Y")
-        kwargs["pkg_release"] = "0"
-        kwargs["rust_group"] = "Development/Libraries/Rust"
-    elif rpmautospec:
-        kwargs["pkg_release"] = "%autorelease"
-    else:
-        kwargs["pkg_release"] = "1%{?dist}"
+    if args.rpmautospec is None:
+        args.rpmautospec = detect_rpmautospec(args.target, spec_file)
 
     if args.dynamic_buildrequires is None:
         args.dynamic_buildrequires = args.target == "fedora"
 
-    kwargs["generate_buildrequires"] = args.dynamic_buildrequires
-
-    if args.target in {"opensuse"}:
-        kwargs["date"] = time.strftime("%a %b %d %T %Z %Y")
-    else:
-        kwargs["date"] = time.strftime("%a %b %d %Y")
     packager_identity = detect_packager()
-    if packager_identity is not None:
-        kwargs["packager"] = packager_identity
-
-    if metadata.license is not None:
-        license, comments = licensing.translate_license(args.target, metadata.license)
-        kwargs["license"] = license
-        kwargs["license_comments"] = comments
-
-    kwargs["doc_files"] = doc_files
-    kwargs["license_files"] = license_files
 
     conf = configparser.ConfigParser(interpolation=configparser.ExtendedInterpolation())
     confs = conf.read([".rust2rpm.conf", "_rust2rpm.conf", "rust2rpm.conf"])
@@ -597,19 +512,24 @@ def main():
     if args.target not in conf:
         conf.add_section(args.target)
 
-    kwargs["distconf"] = conf[args.target]
-
     conf_all_features = conf[args.target].getboolean("all-features")
-    kwargs["all_features"] = conf_all_features or args.all_features
-
     if conf_all_features is False and args.all_features:
         print("WARNING: Conflicting settings for enabling all features: The setting is \"false\"")
         print("         in rust2rpm.conf but it was enabled with the \"--all-features\" CLI flag.")
 
-    spec_contents = template.render(
-        metadata=metadata,
-        patch_file=patch_file,
-        **kwargs)
+    spec_contents = generator.spec_file_render(
+        args = args,
+        pkg_name = pkg_name,
+        crate = crate,
+        metadata = metadata,
+        patch_file = patch_file,
+        packager_identity = packager_identity,
+        doc_files = doc_files,
+        license_files = license_files,
+        distconf = conf[args.target],
+        all_features = conf_all_features or args.all_features,
+    )
+
     if args.stdout:
         print(f"# {spec_file}")
         print(spec_contents)
diff --git a/rust2rpm/generator.py b/rust2rpm/generator.py
new file mode 100644
index 0000000..8e2bf6c
--- /dev/null
+++ b/rust2rpm/generator.py
@@ -0,0 +1,111 @@
+import time
+
+import jinja2
+
+from . import __version__, metadata, licensing
+
+def to_list(s):
+    if not s:
+        return []
+    return list(filter(None, (l.strip() for l in s.splitlines())))
+
+def spec_file_template():
+    env = jinja2.Environment(
+        loader=jinja2.ChoiceLoader([
+            jinja2.FileSystemLoader(['/']),
+            jinja2.PackageLoader('rust2rpm', 'templates'),
+        ]),
+        extensions=['jinja2.ext.do'],
+        trim_blocks=True,
+        lstrip_blocks=True)
+
+    env.globals['normalize_deps'] = metadata.normalize_deps
+    env.globals['to_list'] = to_list
+
+    return env.get_template('main.spec')
+
+def spec_file_render(
+        args,
+        pkg_name,
+        crate,
+        metadata,
+        patch_file,
+        packager_identity,
+        doc_files,
+        license_files,
+        distconf,
+        all_features,
+):
+    template = spec_file_template()
+
+    bins = [tgt for tgt in metadata.targets if tgt.kind == "bin"]
+    libs = [tgt for tgt in metadata.targets if tgt.kind in {"lib", "rlib", "proc-macro"}]
+    is_bin = len(bins) > 0
+    is_lib = len(libs) > 0
+
+    kwargs = {
+        'generator_version': __version__,
+        'target': args.target,
+        'crate': crate,
+        'include_devel': is_lib,
+        'pkg_name': pkg_name,
+        'auto_changelog_entry': args.auto_changelog_entry,
+        'rpmautospec': args.rpmautospec,
+        'relative_license_paths': args.relative_license_paths,
+        'generate_buildrequires': args.dynamic_buildrequires,
+        'doc_files': doc_files,
+        'license_files': license_files,
+        'distconf': distconf,
+        'all_features': all_features,
+    }
+
+    if is_bin:
+        kwargs['include_main'] = True
+        kwargs['bins'] = bins
+    elif is_lib:
+        kwargs['include_main'] = False
+    else:
+        raise ValueError('No bins and no libs')
+
+    if args.target in {'fedora', 'mageia', 'opensuse'}:
+        kwargs['include_build_requires'] = True
+        kwargs['include_provides'] = False
+        kwargs['include_requires'] = False
+    elif args.target == 'plain':
+        kwargs['include_build_requires'] = True
+        kwargs['include_provides'] = True
+        kwargs['include_requires'] = True
+    else:
+        assert False, f'Unknown target {args.target!r}'
+
+    if args.target == 'mageia':
+        kwargs['pkg_release'] = '%mkrel 1'
+        kwargs['rust_group'] = 'Development/Rust'
+    elif args.target == 'opensuse':
+        kwargs['spec_copyright_year'] = time.strftime('%Y')
+        kwargs['pkg_release'] = '0'
+        kwargs['rust_group'] = 'Development/Libraries/Rust'
+    elif args.rpmautospec:
+        kwargs['pkg_release'] = '%autorelease'
+    else:
+        kwargs['pkg_release'] = '1%{?dist}'
+
+    if args.target in {'opensuse'}:
+        kwargs['date'] = time.strftime('%a %b %d %T %Z %Y')
+    else:
+        kwargs['date'] = time.strftime('%a %b %d %Y')
+
+    if packager_identity is not None:
+        kwargs['packager'] = packager_identity
+
+    if metadata.license is not None:
+        license, comments = licensing.translate_license(args.target, metadata.license)
+        kwargs["license"] = license
+        kwargs["license_comments"] = comments
+
+    spec_contents = template.render(
+        metadata=metadata,
+        patch_file=patch_file,
+        **kwargs)
+
+    return spec_contents