diff --git a/backend/persisters/ogc_features.py b/backend/persisters/ogc_features.py
index 29cdda4..282cb27 100644
--- a/backend/persisters/ogc_features.py
+++ b/backend/persisters/ogc_features.py
@@ -136,7 +136,7 @@ def _num(value) -> Optional[float]:
         return None
     try:
         return float(value)
-    except TypeError, ValueError:
+    except (TypeError, ValueError):
         return None
 
 
diff --git a/backend/unifier.py b/backend/unifier.py
index 6b27ea7..2b2c1f6 100644
--- a/backend/unifier.py
+++ b/backend/unifier.py
@@ -148,7 +148,7 @@ def _site_wrapper(site_source, parameter_source, persister, config, raise_errors
 
         try:
             sites = site_source.read()
-        except USGSRateLimitError, PartialOrNoDataError:
+        except (USGSRateLimitError, PartialOrNoDataError):
             config.warn(incomplete_sites_record_msg)
             sites = []
 
diff --git a/backend/well_correlation.py b/backend/well_correlation.py
index df5464f..0a6453c 100644
--- a/backend/well_correlation.py
+++ b/backend/well_correlation.py
@@ -112,7 +112,7 @@ def _num(value: Any) -> Optional[float]:
         return None
     try:
         return float(value)
-    except TypeError, ValueError:
+    except (TypeError, ValueError):
         return None