diff --git a/misc/bash/completion.sh b/misc/bash/completion.sh
index 93298c369..bc184edd6 100644
--- a/misc/bash/completion.sh
+++ b/misc/bash/completion.sh
@@ -1,4 +1,7 @@
 function _complete_nix {
+    local -a words
+    local cword cur
+    _get_comp_words_by_ref -n ':=&' words cword cur
     local have_type
     while IFS= read -r line; do
         if [[ -z $have_type ]]; then
@@ -9,7 +12,8 @@ function _complete_nix {
         else
             COMPREPLY+=("$line")
         fi
-    done < <(NIX_GET_COMPLETIONS=$COMP_CWORD "${COMP_WORDS[@]}")
+    done < <(NIX_GET_COMPLETIONS=$cword "${words[@]}")
+    __ltrim_colon_completions "$cur"
 }
 
 complete -F _complete_nix nix