diff --git a/rdtools/availability.py b/rdtools/availability.py
index 144c5ed8..6ac74fcf 100644
--- a/rdtools/availability.py
+++ b/rdtools/availability.py
@@ -536,6 +536,11 @@ def _combine_losses(self, rollup_period="ME"):
             The period on which to roll up losses and calculate availability.
         """
 
+        # Allow pandas < 2.0 to use 'M' as an alias for MonthEnd
+        # https://pandas.pydata.org/docs/whatsnew/v2.2.0.html#deprecate-aliases-m-q-y-etc-in-favour-of-me-qe-ye-etc-for-offsets
+        if rollup_period == "ME":
+            rollup_period = pd.tseries.offsets.MonthEnd()
+
         if ((self.loss_system > 0) & (self.loss_subsystem > 0)).any():
             msg = (
                 'Loss detected simultaneously at both system and subsystem '
diff --git a/requirements-min.txt b/requirements-min.txt
index d324f7c2..d44d3c0c 100644
--- a/requirements-min.txt
+++ b/requirements-min.txt
@@ -1,6 +1,6 @@
 matplotlib==3.5.3
 numpy==1.22.4
-pandas==1.5.3
+pandas==1.4.4
 statsmodels==0.13.5
 scipy==1.8.1
 h5py==3.7.0
diff --git a/setup.py b/setup.py
index 26231524..0e8f3ab6 100755
--- a/setup.py
+++ b/setup.py
@@ -43,7 +43,7 @@
 INSTALL_REQUIRES = [
     "matplotlib >= 3.5.3",
     "numpy >= 1.22.4",
-    "pandas >= 1.5.3",
+    "pandas >= 1.4.4",
     "statsmodels >= 0.13.5",
     "scipy >= 1.8.1",
     "h5py >= 3.7.0",