diff --git a/python/sphinx_docs/src/opm_python_docs/sphinx_ext_docstrings.py b/python/sphinx_docs/src/opm_python_docs/sphinx_ext_docstrings.py
index 26311c5..c71065c 100644
--- a/python/sphinx_docs/src/opm_python_docs/sphinx_ext_docstrings.py
+++ b/python/sphinx_docs/src/opm_python_docs/sphinx_ext_docstrings.py
@@ -70,7 +70,7 @@ def process_template_docstrings(directive, config):
                 rst.append("", source="")
                 doc = expanded.get("doc", "")
                 if doc:
-                    for line in doc.split('\\n'):  # Handle escaped newlines
+                    for line in doc.split('\n'):
                         rst.append(f"      {line}", source="")
                 rst.append("", source="")
 
@@ -83,7 +83,7 @@ def process_template_docstrings(directive, config):
                 rst.append("", source="")
                 doc = expanded.get("doc", "")
                 if doc:
-                    for line in doc.split('\\n'):  # Handle escaped newlines
+                    for line in doc.split('\n'):
                         rst.append(f"      {line}", source="")
                 rst.append("", source="")
 
@@ -96,7 +96,6 @@ def process_template_docstrings(directive, config):
     return result
 
 def read_doc_strings(directive, docstrings_path):
-    print(docstrings_path)
     with open(docstrings_path, 'r') as file:
         docstrings = json.load(file)
 
diff --git a/python/sphinx_docs/tests/files/docstrings_simulators_template.json b/python/sphinx_docs/tests/files/docstrings_simulators_template.json
new file mode 100644
index 0000000..686f5b5
--- /dev/null
+++ b/python/sphinx_docs/tests/files/docstrings_simulators_template.json
@@ -0,0 +1,21 @@
+{
+    "simulators": {
+        "PyBlackOilSimulator": {
+            "name": "BlackOilSimulator",
+            "class": "PyBlackOilSimulator",
+            "doc": "Simulator for black oil cases."
+        }
+    },
+    "constructors": {
+        "filename_constructor": {
+            "signature_template": "opm.simulators.{{name}}.__init__(filename: str) -> None",
+            "doc": "Constructor from a deck file name.\n\n:param filename: Path to the deck file.\n:type filename: str"
+        }
+    },
+    "common_methods": {
+        "advance": {
+            "signature_template": "opm.simulators.{{name}}.advance(report_step: int) -> None",
+            "doc": "Advances the simulation to a specific report step.\n\n:param report_step: Target report step to advance to.\n:type report_step: int"
+        }
+    }
+}
diff --git a/python/sphinx_docs/tests/test_sphinx_ext_docstrings.py b/python/sphinx_docs/tests/test_sphinx_ext_docstrings.py
new file mode 100644
index 0000000..8183d3f
--- /dev/null
+++ b/python/sphinx_docs/tests/test_sphinx_ext_docstrings.py
@@ -0,0 +1,72 @@
+"""Tests for the JSON -> Sphinx documentation extension.
+
+The template format stores a method's docstring as a single JSON string with
+embedded newlines. The extension has to hand those to docutils one line at a
+time; feeding it the whole docstring as a single line makes docutils treat
+reStructuredText field lists such as ``:param x:`` as ordinary text, so the
+published page shows the markup instead of a parameter table.
+"""
+
+import shutil
+from pathlib import Path
+
+from sphinx.application import Sphinx
+
+
+def build_docs(tmp_path: Path, test_file_path: Path, json_name: str) -> str:
+    """Build a minimal Sphinx project that renders one docstrings JSON file.
+
+    Returns the generated HTML.
+    """
+    srcdir = tmp_path / "src"
+    srcdir.mkdir()
+    shutil.copy(test_file_path / json_name, srcdir / json_name)
+
+    (srcdir / "conf.py").write_text(
+        "extensions = ['opm_python_docs.sphinx_ext_docstrings']\n"
+        f"opm_simulators_docstrings_path = r'{srcdir / json_name}'\n"
+        f"opm_common_docstrings_path = r'{srcdir / json_name}'\n"
+    )
+    (srcdir / "index.rst").write_text(
+        "Test\n"
+        "====\n"
+        "\n"
+        ".. opm_simulators_docstrings::\n"
+    )
+
+    outdir = tmp_path / "out"
+    app = Sphinx(
+        srcdir=str(srcdir),
+        confdir=str(srcdir),
+        outdir=str(outdir),
+        doctreedir=str(tmp_path / "doctrees"),
+        buildername="html",
+    )
+    app.build()
+    return (outdir / "index.html").read_text()
+
+
+def test_template_format_renders_field_lists(
+    tmp_path: Path, test_file_path: Path
+) -> None:
+    """A ``:param:`` in a template-format docstring becomes a parameter table."""
+    html = build_docs(tmp_path, test_file_path, "docstrings_simulators_template.json")
+
+    # The rendered page must not contain the field-list markup as visible text.
+    assert ":param report_step:" not in html
+    assert ":type report_step:" not in html
+
+    # It must contain a real parameter table instead.
+    assert "field-list" in html
+    assert "report_step" in html
+    assert "Target report step to advance to." in html
+
+
+def test_template_format_renders_constructor_field_lists(
+    tmp_path: Path, test_file_path: Path
+) -> None:
+    """Constructors go through a separate code path and need the same handling."""
+    html = build_docs(tmp_path, test_file_path, "docstrings_simulators_template.json")
+
+    assert ":param filename:" not in html
+    assert "Path to the deck file." in html