diff --git a/doc/configuration.rst b/doc/configuration.rst
index 08bebbc7..3555afaf 100644
--- a/doc/configuration.rst
+++ b/doc/configuration.rst
@@ -1092,6 +1092,8 @@ Options
 **createiso_max_size_is_strict**
     (*list*) -- Set the value to ``True`` to turn the warning from
     ``createiso_max_size`` into a hard error that will abort the compose.
+    If there are multiple matches in the mapping, the check will be strict if
+    at least one match says so.
 
     Format: ``[(variant_uid_regex, {arch|*: bool})]``
 
diff --git a/pungi/phases/test.py b/pungi/phases/test.py
index 03f33de3..abd1f7c7 100644
--- a/pungi/phases/test.py
+++ b/pungi/phases/test.py
@@ -182,7 +182,7 @@ def check_size_limit(compose, variant, arch, img):
         msg = "ISO %s is too big. Expected max %dB, got %dB" % (
             img.path, limit, img.size
         )
-        if is_strict:
+        if any(is_strict):
             raise RuntimeError(msg)
         else:
             compose.log_warning(msg)
diff --git a/tests/test_test_phase.py b/tests/test_test_phase.py
index adcd0998..679ef15e 100644
--- a/tests/test_test_phase.py
+++ b/tests/test_test_phase.py
@@ -202,6 +202,27 @@ class TestCheckImageSanity(PungiTestCase):
             "ISO Client/i386/iso/image.iso is too big. Expected max 10B, got 20B",
         )
 
+    @mock.patch("pungi.phases.test.check_sanity", new=mock.Mock())
+    def test_too_big_iso_not_strict(self):
+        compose = DummyCompose(
+            self.topdir,
+            {
+                "createiso_max_size": [(".*", {"*": 10})],
+                "createiso_max_size_is_strict": [(".*", {"*": False})],
+            },
+        )
+        compose.image.format = 'iso'
+        compose.image.bootable = False
+        compose.image.size = 20
+
+        test_phase.check_image_sanity(compose)
+
+        warnings = [call[0][0] for call in compose.log_warning.call_args_list]
+        self.assertIn(
+            "ISO Client/i386/iso/image.iso is too big. Expected max 10B, got 20B",
+            warnings,
+        )
+
     @mock.patch("pungi.phases.test.check_sanity", new=mock.Mock())
     def test_too_big_unified(self):
         compose = DummyCompose(self.topdir, {})