diff --git a/argv/src/script.rs b/argv/src/script.rs
index acb6f548e..997fb8124 100644
--- a/argv/src/script.rs
+++ b/argv/src/script.rs
@@ -454,10 +454,10 @@ def --env __usage_complete_{ident} [spans: list<string>] {{
     let commands = (if $wants_commands {{
         let prefix = ($spans | last)
         let insensitive = $nu.os-info.name == "windows"
-        let match_prefix = if $insensitive {{ $prefix | str downcase }} else {{ $prefix }}
+        let match_prefix = if $insensitive {{ $prefix | str lowercase }} else {{ $prefix }}
         which
         | where {{|row|
-            let candidate = if $insensitive {{ $row.command | str downcase }} else {{ $row.command }}
+            let candidate = if $insensitive {{ $row.command | str lowercase }} else {{ $row.command }}
             $candidate | str starts-with $match_prefix
         }}
         | each {{|row| {{ value: $row.command, description: $row.path }} }}
diff --git a/go/argv/script.go b/go/argv/script.go
index 114c572b9..89e27b9eb 100644
--- a/go/argv/script.go
+++ b/go/argv/script.go
@@ -324,10 +324,10 @@ def --env __usage_complete_{ident} [spans: list<string>] {
     let commands = (if $wants_commands {
         let prefix = ($spans | last)
         let insensitive = $nu.os-info.name == "windows"
-        let match_prefix = if $insensitive { $prefix | str downcase } else { $prefix }
+        let match_prefix = if $insensitive { $prefix | str lowercase } else { $prefix }
         which
         | where {|row|
-            let candidate = if $insensitive { $row.command | str downcase } else { $row.command }
+            let candidate = if $insensitive { $row.command | str lowercase } else { $row.command }
             $candidate | str starts-with $match_prefix
         }
         | each {|row| { value: $row.command, description: $row.path } }