diff --git a/click/core.py b/click/core.py
index 074152872..3acfce6cb 100644
--- a/click/core.py
+++ b/click/core.py
@@ -1567,8 +1567,12 @@ def _parse_decls(self, decls, expose_value):
                     opts.append(decl)
 
         if name is None and possible_names:
-            possible_names.sort(key=lambda x: len(x[0]))
-            name = possible_names[-1][1].replace('-', '_').lower()
+            # From docs: By default, the name of the parameter is the first
+            #            long option defined; otherwise the first short one
+            #            is used.
+            name = ([n for d, n in possible_names if len(d) == 2] +
+                    [n for d, n in possible_names if len(d) == 1])[0]
+            name = name.replace('-', '_').lower()
             if not isidentifier(name):
                 name = None