diff --git a/util/test/rdtest/testcase.py b/util/test/rdtest/testcase.py
index f0b021cae..7e66b5ab0 100644
--- a/util/test/rdtest/testcase.py
+++ b/util/test/rdtest/testcase.py
@@ -35,8 +35,20 @@ class ShaderVariableCheck:
 
         return self
 
+    def truncated(self):
+        if not (self.var.flags & rd.ShaderVariableFlags.Truncated):
+            raise TestFailureException(f"Variable {self.var.name} is not truncated")
+
+        count = self.var.columns
+        if list(self.var.value.u32v[0:count]) != [0] * count:
+                raise TestFailureException(f"Truncated variable {self.var.name} doesn't have 0 values")
+
     def value(self, value_: List[float] | List[int]):
         count = len(value_)
+
+        if self.var.flags & rd.ShaderVariableFlags.Truncated:
+            raise TestFailureException(f"Variable {self.var.name} is truncated but we're checking its value")
+
         if isinstance(value_[0], float):
             vals = []
             if self.var.type == rd.VarType.Float:
diff --git a/util/test/tests/D3D11/D3D11_Parameter_Zoo.py b/util/test/tests/D3D11/D3D11_Parameter_Zoo.py
index 8591b02f7..53b5bf637 100644
--- a/util/test/tests/D3D11/D3D11_Parameter_Zoo.py
+++ b/util/test/tests/D3D11/D3D11_Parameter_Zoo.py
@@ -31,7 +31,7 @@ class D3D11_Parameter_Zoo(rdtest.TestCase):
                                                        pipe.GetShaderEntryPoint(stage), 0,
                                                        cbuf.resource, cbuf.byteOffset, cbuf.byteSize))
 
-        var_check.check('cbuf_zero').rows(1).cols(4).value([0.0, 0.0, 0.0, 0.0])
+        var_check.check('cbuf_zero').rows(1).cols(4).truncated()
 
         tex = rd.TextureDisplay()
         tex.overlay = rd.DebugOverlay.Drawcall
diff --git a/util/test/tests/Vulkan/VK_Robustness2.py b/util/test/tests/Vulkan/VK_Robustness2.py
index 242c72c16..a3172530c 100644
--- a/util/test/tests/Vulkan/VK_Robustness2.py
+++ b/util/test/tests/Vulkan/VK_Robustness2.py
@@ -89,7 +89,7 @@ class VK_Robustness2(rdtest.TestCase):
                                                            cbuf.resource, cbuf.byteOffset, cbuf.byteSize))
 
             if cb.bufferBacked:
-                var_check.check('data').type(rd.VarType.Float).rows(1).cols(4).value([0.0, 0.0, 0.0, 0.0])
+                var_check.check('data').type(rd.VarType.Float).rows(1).cols(4).truncated()
             else:
                 val = [0, 0, 0, 0]
                 if self.find_action('robustBufferAccess2') is not None: