diff --git a/changelog/74.improvement.md b/changelog/74.improvement.md
new file mode 100644
index 0000000..d5ca8b4
--- /dev/null
+++ b/changelog/74.improvement.md
@@ -0,0 +1 @@
+Improved the error message if regexp parsing of paths fails for a given DRS.
diff --git a/src/input4mips_validation/cvs/drs.py b/src/input4mips_validation/cvs/drs.py
index a1c51f1..8e6e930 100644
--- a/src/input4mips_validation/cvs/drs.py
+++ b/src/input4mips_validation/cvs/drs.py
@@ -373,7 +373,7 @@ def extract_metadata_from_path(
         )
         match = re.match(directory_regexp, str(directory))
         if match is None:
-            msg = "regexp failed"
+            msg = f"regexp failed. {directory_regexp=}. {directory=}"
             raise AssertionError(msg)
 
         match_groups = match.groupdict()
@@ -451,7 +451,7 @@ def extract_metadata_from_filename(self, filename: str) -> dict[str, str | None]
         filename_regexp = self.get_regexp_for_capturing_filename_information()
         match = re.match(filename_regexp, filename)
         if match is None:
-            msg = "regexp failed"
+            msg = f"regexp failed. {filename_regexp=}. {filename=}"
             raise AssertionError(msg)
 
         match_groups = match.groupdict()
diff --git a/tests/unit/cvs/test_drs_path_handling.py b/tests/unit/cvs/test_drs_path_handling.py
new file mode 100644
index 0000000..b5ef503
--- /dev/null
+++ b/tests/unit/cvs/test_drs_path_handling.py
@@ -0,0 +1,102 @@
+"""
+Tests of path parsing with the DRS
+"""
+
+from contextlib import nullcontext as does_not_raise
+
+import pytest
+
+from input4mips_validation.cvs.drs import DataReferenceSyntax
+
+
+@pytest.mark.parametrize(
+    "directory_path_template, directory, exp_raise, exp_res",
+    (
+        (
+            "<activity_id>/<mip_era>/<target_mip>/<institution_id>/<source_id>/<realm>/<frequency>/<variable_id>/<grid_label>/v<version>",
+            "/root/input4MIPs/CMIP6Plus/CMIP/PCMDI/PCMDI-AMIP-1-1-9/ocean/mon/tos/gn/v20230512/",
+            does_not_raise(),
+            {
+                "activity_id": "input4MIPs",
+                "frequency": "mon",
+                "grid_label": "gn",
+                "institution_id": "PCMDI",
+                "mip_era": "CMIP6Plus",
+                "realm": "ocean",
+                "source_id": "PCMDI-AMIP-1-1-9",
+                "target_mip": "CMIP",
+                "variable_id": "tos",
+                "version": "20230512",
+            },
+        ),
+        pytest.param(
+            "<activity_id>/<mip_era>/<target_mip>/<institution_id>/<source_id>/<realm>/<frequency>/<variable_id>/<grid_label>/v<version>",
+            "input4MIPs/CMIP/PCMDI/PCMDI-AMIP-1-1-9/ocean/mon/tos/gn/v20230512/",
+            pytest.raises(
+                AssertionError,
+                match="regexp failed. directory_regexp='.*'. directory='.*'",
+            ),
+            None,
+            id="missing_mip_era",
+        ),
+    ),
+)
+def test_extract_metadata_from_path(
+    directory_path_template, directory, exp_raise, exp_res
+):
+    drs = DataReferenceSyntax(
+        directory_path_template=directory_path_template,
+        directory_path_example="not_used",
+        filename_template="not_used",
+        filename_example="not_used",
+    )
+    with exp_raise:
+        res = drs.extract_metadata_from_path(directory)
+
+    if exp_res is not None:
+        assert res == exp_res
+
+
+@pytest.mark.parametrize(
+    "filename_template, filename, exp_raise, exp_res",
+    (
+        (
+            "<variable_id>_<activity_id>_<dataset_category>_<target_mip>_<source_id>_<grid_label>[_<time_range>].nc",
+            "tos_input4MIPs_SSTsAndSeaIce_CMIP_PCMDI-AMIP-1-1-9_gn_187001-202212.nc",
+            does_not_raise(),
+            {
+                "activity_id": "input4MIPs",
+                "dataset_category": "SSTsAndSeaIce",
+                "grid_label": "gn",
+                "source_id": "PCMDI-AMIP-1-1-9",
+                "target_mip": "CMIP",
+                "time_range": "187001-202212",
+                "variable_id": "tos",
+            },
+        ),
+        pytest.param(
+            "<variable_id>_<activity_id>_<dataset_category>_<target_mip>_<source_id>_<grid_label>[_<time_range>].nc",
+            "tos_percentage_input4MIPs_SSTsAndSeaIce_CMIP_PCMDI-AMIP-1-1-9_gn_187001-202212.nc",
+            pytest.raises(
+                AssertionError,
+                match="regexp failed. filename_regexp='.*'. filename='.*'",
+            ),
+            None,
+            id="underscore_in_variable_id",
+        ),
+    ),
+)
+def test_extract_metadata_from_filename(
+    filename_template, filename, exp_raise, exp_res
+):
+    drs = DataReferenceSyntax(
+        directory_path_template="not_used",
+        directory_path_example="not_used",
+        filename_template=filename_template,
+        filename_example="not_used",
+    )
+    with exp_raise:
+        res = drs.extract_metadata_from_filename(filename)
+
+    if exp_res is not None:
+        assert res == exp_res