diff --git a/pyproject.toml b/pyproject.toml
index a77ca34..05ef19f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -38,7 +38,7 @@ requires = [
     "wellpathpy",
     "matplotlib",
     "numpy",
-    "pandas",
+    "pandas==2.1.1",
     "scipy"
 ]
 test_requires = [
@@ -49,7 +49,7 @@ test_requires = [
     "wellpathpy",
     "matplotlib",
     "numpy",
-    "pandas",
+    "pandas==2.1.1",
     "scipy"
     
 ]