diff --git a/babelizer/data/cookiecutter.json b/babelizer/data/cookiecutter.json
index 3c2432eb..920018d9 100644
--- a/babelizer/data/cookiecutter.json
+++ b/babelizer/data/cookiecutter.json
@@ -6,7 +6,8 @@
     "libraries": [],
     "library_dirs": [],
     "include_dirs": [],
-    "extra_compile_args": []
+    "extra_compile_args": [],
+    "max_instances": 3
   },
   "info": {
     "full_name": "CSDMS",
diff --git a/babelizer/data/{{cookiecutter.package_name}}/{{cookiecutter.package_name}}/lib/bmi_interoperability.f90 b/babelizer/data/{{cookiecutter.package_name}}/{{cookiecutter.package_name}}/lib/bmi_interoperability.f90
index 91ba3049..80bf7580 100644
--- a/babelizer/data/{{cookiecutter.package_name}}/{{cookiecutter.package_name}}/lib/bmi_interoperability.f90
+++ b/babelizer/data/{{cookiecutter.package_name}}/{{cookiecutter.package_name}}/lib/bmi_interoperability.f90
@@ -17,7 +17,7 @@ module bmi_interoperability
 
   implicit none
 
-  integer, parameter :: N_MODELS = 2048
+  integer, parameter :: N_MODELS = {{ cookiecutter.build.max_instances }}
   type ({{ component.entry_point }}) :: model_array(N_MODELS)
   logical :: model_avail(N_MODELS) = .true.
 
diff --git a/babelizer/metadata.py b/babelizer/metadata.py
index 03be4d76..5bee02d0 100644
--- a/babelizer/metadata.py
+++ b/babelizer/metadata.py
@@ -230,6 +230,7 @@ def validate(config):
                 "library_dirs",
                 "include_dirs",
                 "extra_compile_args",
+                "max_instances",
             ),
         )
         validate_dict(config["package"], required=("name", "requirements"), optional={})
@@ -313,6 +314,9 @@ def norm(config):
         except KeyError:
             pass
 
+        if "max_instances" not in build:
+            build["max_instances"] = 8
+
         if "entry_point" in config["library"]:
             libraries = BabelMetadata._handle_old_style_entry_points(config["library"])
         else:
@@ -335,6 +339,7 @@ def norm(config):
                 "library_dirs": build["library_dirs"],
                 "include_dirs": build["include_dirs"],
                 "extra_compile_args": build["extra_compile_args"],
+                "max_instances": build["max_instances"],
             },
             "package": {
                 "name": config["package"]["name"],
@@ -446,6 +451,7 @@ def as_cookiecutter_context(self):
                 "library_dirs": self._meta["build"]["library_dirs"],
                 "include_dirs": self._meta["build"]["include_dirs"],
                 "extra_compile_args": self._meta["build"]["extra_compile_args"],
+                "max_instances": self._meta["build"]["max_instances"],
             },
             "info": {
                 "full_name": self._meta["info"]["package_author"],
diff --git a/external/tests/test_fortran.py b/external/tests/test_fortran.py
index f1a5fba9..905a6d2a 100644
--- a/external/tests/test_fortran.py
+++ b/external/tests/test_fortran.py
@@ -6,6 +6,9 @@
 import subprocess
 import sys
 
+import git
+import pytest
+import toml
 from click.testing import CliRunner
 
 from babelizer.cli import babelize
@@ -16,17 +19,59 @@
     extra_opts += ["--no-build-isolation"]
 
 
-def test_babelize_init_fortran(tmpdir, datadir):
-    runner = CliRunner()
+@pytest.mark.dependency()
+def test_babelize_init_works(tmpdir, datadir):
+    runner = CliRunner(mix_stderr=False)
+    with tmpdir.as_cwd():
+        result = runner.invoke(babelize, ["init", str(datadir / "babel.toml")])
+
+        assert result.stdout.strip() == str(tmpdir / "pymt_heatf")
+        assert result.exit_code == 0
+        assert pathlib.Path("pymt_heatf").exists()
+        assert (pathlib.Path("pymt_heatf") / "babel.toml").is_file()
+
+        repo = git.Repo("pymt_heatf")
+
+        assert not repo.bare
+
+
+@pytest.mark.dependency(depends=["test_babelize_init_works"])
+@pytest.mark.parametrize("max_instances", [8, 32, None])
+def test_babelize_init_fortran_with_user_instances(tmpdir, datadir, max_instances):
+    runner = CliRunner(mix_stderr=False)
+
+    babel_toml = toml.load(datadir / "babel.toml")
+    babel_toml["build"]["max_instances"] = max_instances
+
+    if max_instances is None:
+        babel_toml["build"].pop("max_instances", None)
+        max_instances = 8
 
     with tmpdir.as_cwd():
-        shutil.copy(datadir / "babel.toml", ".")
+        with open("babel.toml", "w") as fp:
+            toml.dump(babel_toml, fp)
+
         result = runner.invoke(babelize, ["init", "babel.toml"])
 
+        assert result.stdout.strip() == str(tmpdir / "pymt_heatf")
         assert result.exit_code == 0
         assert pathlib.Path("pymt_heatf").exists()
         assert (pathlib.Path("pymt_heatf") / "babel.toml").is_file()
 
+        meta = toml.load("pymt_heatf/babel.toml")
+
+        assert "max_instances" in meta["build"]
+        assert meta["build"]["max_instances"] == max_instances
+
+
+@pytest.mark.dependency(depends=["test_babelize_init_works"])
+def test_babelize_build_fortran_example(tmpdir, datadir):
+    runner = CliRunner(mix_stderr=False)
+
+    with tmpdir.as_cwd():
+        runner.invoke(babelize, ["init", str(datadir / "babel.toml")])
+
+    with tmpdir.as_cwd():
         try:
             result = subprocess.run(
                 ["pip", "install", "-e", "."] + extra_opts,
@@ -63,3 +108,18 @@ def test_babelize_init_fortran(tmpdir, datadir):
             assert err.output is None, err.output
 
         assert result.returncode == 0
+
+
+@pytest.mark.dependency(depends=["test_babelize_init_works"])
+def test_babelize_update_fortran(tmpdir, datadir):
+    runner = CliRunner(mix_stderr=False)
+
+    with tmpdir.as_cwd():
+        runner.invoke(babelize, ["init", str(datadir / "babel.toml")])
+
+    with tmpdir.as_cwd():
+        result = runner.invoke(babelize, ["--cd", "pymt_heatf", "update"])
+
+        assert result.exit_code == 0
+        assert pathlib.Path("pymt_heatf").exists()
+        assert "re-rendering" in result.stderr