diff --git a/pyproject.toml b/pyproject.toml
index d86eb0650..60e1e3111 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -29,7 +29,7 @@ dependencies = ["ansys-dpf-core>=0.7.2",
                 "ansys-tools-path>=0.6.0",
                 "ansys-platform-instancemanagement~=1.0",
                 "pyvista>=0.43.4",
-                "hollerith==0.4.1",
+                "hollerith>=0.4.1",
                 "numpy>=1",
                 "pandas>=2.0",
                 "appdirs>=1.4.4"
@@ -38,6 +38,7 @@ dependencies = ["ansys-dpf-core>=0.7.2",
 [project.optional-dependencies]
 tests = [
     "matplotlib==3.9.2",
+    "hollerith==0.5.0",
     "numpy==2.1.3",
     "pytest==8.3.3",
     "pytest-cov==6.0.0",