diff --git a/src/util/sorted.scad b/src/util/sorted.scad
index 85231b49..13e55b3a 100644
--- a/src/util/sorted.scad
+++ b/src/util/sorted.scad
@@ -11,6 +11,7 @@
 use <_impl/_sorted_impl.scad>;
 
 function sorted(lt, cmp = undef, key = undef) = 
-    !is_undef(cmp) ? _sorted_cmp(lt, cmp) :
-    !is_undef(key) ? _sorted_key(lt, key) :
-                     _sorted_default(lt);
\ No newline at end of file
+    let(is_cmp_undef = is_undef(cmp))
+    is_cmp_undef && is_undef(key) ? _sorted_default(lt) :
+    is_cmp_undef ?                  _sorted_key(lt, key) :
+                                    _sorted_cmp(lt, cmp);
\ No newline at end of file