diff --git a/src/keri/db/basing.py b/src/keri/db/basing.py
index 8294cf551..7426ae733 100644
--- a/src/keri/db/basing.py
+++ b/src/keri/db/basing.py
@@ -939,7 +939,11 @@ def __init__(self, headDirPath=None, reopen=False, **kwa):
         self._kevers.db = self  # assign db for read through cache of kevers
 
         if (mapSize := os.getenv(KERIBaserMapSizeKey)) is not None:
-            self.MapSize = int(mapSize)
+            try:
+                self.MapSize = int(mapSize)
+            except ValueError:
+                logger.error("KERI_BASER_MAP_SIZE must be an integer value >1!")
+                raise
 
         super(Baser, self).__init__(headDirPath=headDirPath, reopen=reopen, **kwa)
 
diff --git a/tests/db/test_basing.py b/tests/db/test_basing.py
index 43d575007..89044c7d9 100644
--- a/tests/db/test_basing.py
+++ b/tests/db/test_basing.py
@@ -2338,6 +2338,22 @@ def test_group_members():
 
     """End Test"""
 
+def test_KERI_BASER_MAP_SIZE_handles_bad_values(caplog):
+    # Base case works because of above tests, they will all break if happy path
+    # is broken.  We'll just test some unhappy values.
+
+    # Pytest will fail if any exceptions raised here.
+    os.environ["KERI_BASER_MAP_SIZE"] = "foo" # Not an int
+    err_msg = "KERI_BASER_MAP_SIZE must be an integer value > 1!"
+    with pytest.raises(ValueError):
+        Baser(reopen=False, temp=True)
+        assert err_msg in caplog.messages
+    os.environ["KERI_BASER_MAP_SIZE"] = "1.0" # Not an int
+    with pytest.raises(ValueError):
+        Baser(reopen=False, temp=True)
+        assert err_msg in caplog.messages
+    os.environ.pop("KERI_BASER_MAP_SIZE")
+
 
 if __name__ == "__main__":
     test_baser()