diff --git a/tests/test_factory_constructors.py b/tests/test_factory_constructors.py
index a9004cbf6..d10aecce1 100644
--- a/tests/test_factory_constructors.py
+++ b/tests/test_factory_constructors.py
@@ -1,3 +1,4 @@
+import gc
 import re
 
 import pytest
@@ -209,6 +210,7 @@ def test_init_factory_alias():
     assert ConstructorStats.detail_reg_inst() == n_inst + 3
     assert [i.alive() for i in cstats] == [3, 3]
     del x, y, z
+    gc.collect()
     assert [i.alive() for i in cstats] == [0, 0]
     assert ConstructorStats.detail_reg_inst() == n_inst
 
@@ -288,9 +290,11 @@ def test_init_factory_dual():
     assert ConstructorStats.detail_reg_inst() == n_inst + 13
 
     del a1, a2, b1, d1, e1, e2
+    gc.collect()
     assert [i.alive() for i in cstats] == [7, 4]
     assert ConstructorStats.detail_reg_inst() == n_inst + 7
     del b2, c1, c2, d2, f1, f2, g1
+    gc.collect()
     assert [i.alive() for i in cstats] == [0, 0]
     assert ConstructorStats.detail_reg_inst() == n_inst
 
diff --git a/tests/test_virtual_functions.py b/tests/test_virtual_functions.py
index c17af7df5..b1ac323e2 100644
--- a/tests/test_virtual_functions.py
+++ b/tests/test_virtual_functions.py
@@ -1,3 +1,5 @@
+import gc
+
 import pytest
 
 import env  # noqa: F401
@@ -81,6 +83,7 @@ def test_override(capture, msg):
     cstats = ConstructorStats.get(m.ExampleVirt)
     assert cstats.alive() == 3
     del ex12, ex12p, ex12p2
+    gc.collect()  # Python 3.13 incremental gc needs this
     assert cstats.alive() == 0
     assert cstats.values() == ["10", "11", "17"]
     assert cstats.copy_constructions == 0