diff --git a/src/param/enums.rs b/src/param/enums.rs
index f5ec6a66..c3985080 100644
--- a/src/param/enums.rs
+++ b/src/param/enums.rs
@@ -173,7 +173,7 @@ impl Param for EnumParamInner {
     }
 
     fn step_count(&self) -> Option<usize> {
-        Some(self.len())
+        Some(self.len() - 1)
     }
 
     fn plain_value(&self) -> Self::Plain {