diff --git a/swh/loader/package/nixguix/loader.py b/swh/loader/package/nixguix/loader.py
--- a/swh/loader/package/nixguix/loader.py
+++ b/swh/loader/package/nixguix/loader.py
@@ -63,8 +63,11 @@
 
     def __init__(self, url):
         super().__init__(url=url)
+        unsupported_file_extensions = self.config.get("unsupported_file_extensions", [])
         self.raw_sources = retrieve_sources(url)
-        clean = clean_sources(parse_sources(self.raw_sources))
+        clean = clean_sources(
+            parse_sources(self.raw_sources), unsupported_file_extensions
+        )
         self.sources = clean["sources"]
         self.provider_url = url
 
@@ -214,13 +217,19 @@
     return json.loads(raw_sources.decode("utf-8"))
 
 
-# Known unsupported archive so far
-PATTERN_KNOWN_UNSUPPORTED_ARCHIVE = re.compile(
-    r".*\.(iso|whl|gem|pom|msi|pod|png|rock|ttf|jar|c|rpm|diff|patch)$", re.DOTALL
-)
+def make_pattern_unsupported_file_extension(unsupported_file_extensions: List[str],):
+    """Make a regexp pattern for unsupported file extension out of a list
+    of unsupported archive extension list.
+
+    """
+    return re.compile(
+        rf".*\.({'|'.join(map(re.escape, unsupported_file_extensions))})$", re.DOTALL
+    )
 
 
-def clean_sources(sources: Dict[str, Any]) -> Dict[str, Any]:
+def clean_sources(
+    sources: Dict[str, Any], unsupported_file_extensions=[]
+) -> Dict[str, Any]:
     """Validate and clean the sources structure. First, ensure all top level keys are
     present. Then, walk the sources list and remove sources that do not contain required
     keys.
@@ -229,6 +238,7 @@
     - required keys are missing
     - source type is not supported
     - urls attribute type is not a list
+    - extension is known not to be supported by the loader
 
     Raises:
         ValueError if:
@@ -236,9 +246,12 @@
         - top-level version is not 1
 
     Returns:
-        Dict sources
+        source Dict cleaned up
 
     """
+    pattern_unsupported_file = make_pattern_unsupported_file_extension(
+        unsupported_file_extensions
+    )
     # Required top level keys
     required_keys = ["version", "revision", "sources"]
     missing_keys = []
@@ -287,7 +300,7 @@
         if valid and len(source["urls"]) > 0:  # Filter out unsupported archives
             supported_sources: List[str] = []
             for source_url in source["urls"]:
-                if PATTERN_KNOWN_UNSUPPORTED_ARCHIVE.match(source_url):
+                if pattern_unsupported_file.match(source_url):
                     logger.info(f"Skip unsupported artifact url {source_url}")
                     continue
                 supported_sources.append(source_url)
@@ -296,7 +309,7 @@
                 logger.info(
                     f"Skip source {source} because urls only reference "
                     "unsupported artifacts. Unsupported "
-                    f"artifacts so far: {PATTERN_KNOWN_UNSUPPORTED_ARCHIVE}"
+                    f"artifacts so far: {pattern_unsupported_file}"
                 )
                 continue
 
diff --git a/swh/loader/package/nixguix/tests/conftest.py b/swh/loader/package/nixguix/tests/conftest.py
new file mode 100644
--- /dev/null
+++ b/swh/loader/package/nixguix/tests/conftest.py
@@ -0,0 +1,33 @@
+# Copyright (C) 2020 The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+import pytest
+
+from typing import Any, Dict
+
+
+@pytest.fixture
+def swh_loader_config(swh_storage_backend_config) -> Dict[str, Any]:
+    # nixguix loader needs a pg-storage backend because some tests share data
+    return {
+        "storage": swh_storage_backend_config,
+        "unsupported_file_extensions": [
+            "patch",
+            "iso",
+            "whl",
+            "gem",
+            "pom",
+            "msi",
+            "pod",
+            "png",
+            "rock",
+            "ttf",
+            "jar",
+            "c",
+            "el",
+            "rpm",
+            "diff",
+        ],
+    }
diff --git a/swh/loader/package/nixguix/tests/test_nixguix.py b/swh/loader/package/nixguix/tests/test_nixguix.py
--- a/swh/loader/package/nixguix/tests/test_nixguix.py
+++ b/swh/loader/package/nixguix/tests/test_nixguix.py
@@ -33,6 +33,7 @@
     parse_sources,
     retrieve_sources,
     clean_sources,
+    make_pattern_unsupported_file_extension,
 )
 
 from swh.loader.package.utils import download
@@ -166,7 +167,45 @@
     assert len(clean["sources"]) == len(valid_sources)
 
 
+def test_make_pattern_unsupported_file_extension():
+    unsupported_extensions = ["el", "c", "txt"]
+    supported_extensions = ["Z", "7z"]  # for test
+
+    actual_unsupported_pattern = make_pattern_unsupported_file_extension(
+        unsupported_extensions
+    )
+
+    for supported_ext in supported_extensions:
+        assert supported_ext not in unsupported_extensions
+
+        supported_filepath = f"anything.{supported_ext}"
+        actual_match = actual_unsupported_pattern.match(supported_filepath)
+        assert not actual_match
+
+    for unsupported_ext in unsupported_extensions:
+        unsupported_filepath = f"something.{unsupported_ext}"
+        actual_match = actual_unsupported_pattern.match(unsupported_filepath)
+        assert actual_match
+
+
 def test_clean_sources_unsupported_artifacts(swh_config, requests_mock_datadir):
+    unsupported_file_extensions = [
+        "iso",
+        "whl",
+        "gem",
+        "pom",
+        "msi",
+        "pod",
+        "png",
+        "rock",
+        "ttf",
+        "jar",
+        "c",
+        "el",
+        "rpm",
+        "diff",
+        "patch",
+    ]
     supported_sources = [
         {
             "type": "url",
@@ -195,22 +234,7 @@
             "urls": [f"https://server.org/my-url.{ext}"],
             "integrity": "my-integrity",
         }
-        for ext in [
-            "iso",
-            "whl",
-            "gem",
-            "pom",
-            "msi",
-            "pod",
-            "png",
-            "rock",
-            "ttf",
-            "jar",
-            "c",
-            "rpm",
-            "diff",
-            "patch",
-        ]
+        for ext in unsupported_file_extensions
     ]
 
     sources = {
@@ -219,7 +243,7 @@
         "revision": "my-revision",
     }
 
-    clean = clean_sources(sources)
+    clean = clean_sources(sources, unsupported_file_extensions)
 
     assert len(clean["sources"]) == len(supported_sources)