diff --git a/pyproject.toml b/pyproject.toml
index 5599fa5597045a444cf3ea480bc9542fae0bd76b..34ea255ac1480d7e4ecc5d1cb2c8fcc0e4e95556 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -58,8 +58,7 @@ all = [
   "scikit-learn >=1.2,<=1.7.2",
   "spgl1 >= 0.0.3,<= 1.0.0",
   "sympy >=1.5,<=1.14.0",
-  # xlwings > 0.30.4 fails test with multi-threading.
-  "xlwings >=0.27.0,<=0.30.4 ; platform_system=='Windows'",
+  "xlwings >=0.27.0,<=0.33.16 ; platform_system=='Windows'",
 ]
 
 [dependency-groups]
diff --git a/requirements/doc.txt b/requirements/doc.txt
index 7398f959d73dc96941dd0da8d8060e56c8552d44..948d8759688d2466741dcb81e06bac9875ddb69f 100644
--- a/requirements/doc.txt
+++ b/requirements/doc.txt
@@ -18,7 +18,7 @@ beautifulsoup4==4.14.2
     # via pydata-sphinx-theme
 certifi==2025.10.5
     # via requests
-charset-normalizer==3.4.3
+charset-normalizer==3.4.4
     # via requests
 contourpy==1.3.3
     # via matplotlib
diff --git a/requirements/test-python3.10.txt b/requirements/test-python3.10.txt
index b3780a01e342445ef1fe856d7a3310b0b43e6390..2461f2285ce22c76f8ba1adaa351b669cd6b83fc 100644
--- a/requirements/test-python3.10.txt
+++ b/requirements/test-python3.10.txt
@@ -4,7 +4,7 @@ annotated-types==0.7.0
     # via pydantic
 certifi==2025.10.5
     # via requests
-charset-normalizer==3.4.3
+charset-normalizer==3.4.4
     # via requests
 contourpy==1.3.2
     # via matplotlib
diff --git a/requirements/test-python3.11.txt b/requirements/test-python3.11.txt
index 1e613fc25e2399788dc32762a631aed21e0c5a16..07601ff6e455115b178d7506f6546a93909d2e51 100644
--- a/requirements/test-python3.11.txt
+++ b/requirements/test-python3.11.txt
@@ -4,7 +4,7 @@ annotated-types==0.7.0
     # via pydantic
 certifi==2025.10.5
     # via requests
-charset-normalizer==3.4.3
+charset-normalizer==3.4.4
     # via requests
 contourpy==1.3.3
     # via matplotlib
diff --git a/requirements/test-python3.12.txt b/requirements/test-python3.12.txt
index b760cf54b966d90ffe7379df600fa142ade83500..fdd7124a45bd9e0e0473b355fded29d6e1b58dd0 100644
--- a/requirements/test-python3.12.txt
+++ b/requirements/test-python3.12.txt
@@ -4,7 +4,7 @@ annotated-types==0.7.0
     # via pydantic
 certifi==2025.10.5
     # via requests
-charset-normalizer==3.4.3
+charset-normalizer==3.4.4
     # via requests
 contourpy==1.3.3
     # via matplotlib
diff --git a/requirements/test-python3.13.txt b/requirements/test-python3.13.txt
index c20b91ee22e90ff79ec4678fca3bde4ba7f366d4..eb6d1d9b38c1392107a08c2ab032f47aa958a79b 100644
--- a/requirements/test-python3.13.txt
+++ b/requirements/test-python3.13.txt
@@ -4,7 +4,7 @@ annotated-types==0.7.0
     # via pydantic
 certifi==2025.10.5
     # via requests
-charset-normalizer==3.4.3
+charset-normalizer==3.4.4
     # via requests
 contourpy==1.3.3
     # via matplotlib