diff --git a/boltons/fileutils.py b/boltons/fileutils.py
index a5157a6..66d338f 100644
--- a/boltons/fileutils.py
+++ b/boltons/fileutils.py
@@ -381,11 +381,11 @@ def copy_tree(src, dst, symlinks=False, ignore=None):
         # continue with other files
         except Error as e:
             errors.extend(e.args[0])
-        except EnvironmentError, why:
+        except EnvironmentError as why:
             errors.append((srcname, dstname, str(why)))
     try:
         copystat(src, dst)
-    except OSError, why:
+    except OSError as why:
         if WindowsError is not None and isinstance(why, WindowsError):
             # Copying file access times may fail on Windows
             pass