diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4245aaa8a..338f58e07 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,9 @@
 - add validators to `rotation-1.0.0.yaml`
   & `gas_component-1.0.0.yaml` [[#303]](https://github.com/BAMWelDX/weldx/pull/303)
 
+### fixes
+
+- prevent creation of `IsoBaseGroove` with negative parameters [[#306]](https://github.com/BAMWelDX/weldx/pull/306)
 
 ## 0.3.1 (21.03.2021)
 
diff --git a/tests/asdf_tests/test_asdf_groove.py b/tests/asdf_tests/test_asdf_groove.py
index e883583c8..29902a2f4 100644
--- a/tests/asdf_tests/test_asdf_groove.py
+++ b/tests/asdf_tests/test_asdf_groove.py
@@ -94,6 +94,16 @@ def test_asdf_groove_exceptions():
             code_number="6.1.1",
         ).to_profile()
 
+    # negative parameter value
+    with pytest.raises(ValueError):
+        get_groove(
+            groove_type="VGroove",
+            workpiece_thickness=Q_(9, "mm"),
+            groove_angle=Q_(50, "deg"),
+            root_face=Q_(-4, "mm"),
+            root_gap=Q_(2, "mm"),
+        )
+
 
 @pytest.mark.parametrize("groove", test_params.values(), ids=test_params.keys())
 def test_cross_section(groove):  # noqa
diff --git a/weldx/welding/groove/iso_9692_1.py b/weldx/welding/groove/iso_9692_1.py
index c3264b9d1..d70c5f2c5 100644
--- a/weldx/welding/groove/iso_9692_1.py
+++ b/weldx/welding/groove/iso_9692_1.py
@@ -81,6 +81,12 @@ class IsoBaseGroove(metaclass=abc.ABCMeta):
     _AREA_RASTER_WIDTH = 0.1
     """steers the area approximation of the groove in ~cross_sect_area."""
 
+    def __post_init__(self):
+        """Make sure all parameters are valid after class init."""
+        for key, value in self.parameters().items():
+            if value < 0.0:
+                raise ValueError(f"Invalid value for parameter {key}={value:~}")
+
     def parameters(self):
         """Return groove parameters as dictionary of quantities."""
         return {k: v for k, v in self.__dict__.items() if isinstance(v, pint.Quantity)}
@@ -1719,6 +1725,11 @@ def get_groove(
                    root_face=Q_(3, "mm"),
                    root_gap=Q_(1, "mm"))
 
+    Raises
+    ------
+    ValueError
+        When passing negative parameter values.
+
     Notes
     -----
     Each groove type has a different set of attributes which are required. Only