diff --git a/tests/conftest.py b/tests/conftest.py
index 0e16ddb..19c745f 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -25,8 +25,7 @@ def _write_function(mesh, el, f, dtype, name="uh", append: bool = False) -> str:
         uh.interpolate(f)
         uh.name = name
         el_hash = (
-            V.element.signature()
-            .replace(" ", "")
+            V.element.signature.replace(" ", "")
             .replace(",", "")
             .replace("(", "")
             .replace(")", "")
@@ -98,8 +97,7 @@ def _write_function_time_dep(mesh, el, f0, f1, t0, t1, dtype) -> str:
         uh = dolfinx.fem.Function(V, dtype=dtype)
         uh.interpolate(f0)
         el_hash = (
-            V.element.signature()
-            .replace(" ", "")
+            V.element.signature.replace(" ", "")
             .replace(",", "")
             .replace("(", "")
             .replace(")", "")
diff --git a/tests/test_original_checkpoint.py b/tests/test_original_checkpoint.py
index 609e33f..425431b 100644
--- a/tests/test_original_checkpoint.py
+++ b/tests/test_original_checkpoint.py
@@ -128,8 +128,7 @@ def write_function_original(
     uh.interpolate(f)
     uh.name = name
     el_hash = (
-        V.element.signature()
-        .replace(" ", "")
+        V.element.signature.replace(" ", "")
         .replace(",", "")
         .replace("(", "")
         .replace(")", "")
@@ -219,8 +218,7 @@ def write_function_vector(
     uh.interpolate(f)
     uh.name = name
     el_hash = (
-        V.element.signature()
-        .replace(" ", "")
+        V.element.signature.replace(" ", "")
         .replace(",", "")
         .replace("(", "")
         .replace(")", "")