diff --git a/util/test/tests/Iter_Test.py b/util/test/tests/Iter_Test.py
index 43fe94f37..628b87f30 100644
--- a/util/test/tests/Iter_Test.py
+++ b/util/test/tests/Iter_Test.py
@@ -350,14 +350,21 @@ class Iter_Test(rdtest.TestCase):
                         if debugged.value.u32v[idx] == 0xcccccccc:
                             debuggedValue[idx] = lastmod.shaderOut.col.floatValue[idx]
 
+                    historyValue = list(lastmod.shaderOut.col.floatValue)
+
+                    tex = self.get_texture(target)
+
+                    historyValue = historyValue[0:tex.format.compCount]
+                    debuggedValue = debuggedValue[0:tex.format.compCount]
+
                     # Unfortunately we can't ever trust that we should get back a matching results, because some shaders
                     # rely on undefined/inaccurate maths that we don't emulate.
                     # So the best we can do is log an error for manual verification
-                    is_eq, diff_amt = rdtest.value_compare_diff(lastmod.shaderOut.col.floatValue, debuggedValue, eps=5.0E-06)
+                    is_eq, diff_amt = rdtest.value_compare_diff(historyValue, debuggedValue, eps=5.0E-06)
                     if not is_eq:
                         rdtest.log.error(
                             "Debugged value {} at EID {} {},{}: {} difference. {} doesn't exactly match history shader output {}".format(
-                                debugged.name, lastmod.eventId, x, y, diff_amt, debuggedValue, lastmod.shaderOut.col.floatValue))
+                                debugged.name, lastmod.eventId, x, y, diff_amt, debuggedValue, historyValue))
 
                     rdtest.log.success('Successfully debugged pixel in {} cycles, result matches'.format(cycles))
                 else: