diff --git a/nix/start-powerline.sh b/nix/start-powerline.sh
index d6d6532de..2f1f804b8 100644
--- a/nix/start-powerline.sh
+++ b/nix/start-powerline.sh
@@ -1,70 +1,70 @@
 #!/usr/bin/env bash
 
 # Check if shell is using a default BSD or GNU prompt
 if [[ ${PS1} != '\s-\v\$'* ]] && \
     [[ ${PS1} != '%n@%m %1~ %#'* ]]; then
   # User already has an opinionated PS1, just leave
   return 0
 fi
 
 if test "$(uname)" = "Darwin" ; then
   COMM_CACHE="${XDG_CACHE_HOME:-$HOME/Library/Caches}/app.comm"
 else
   COMM_CACHE="${XDG_CACHE_HOME:-$HOME/.cache}/comm"
 fi
 
 COMM_EMITTED_WARNING="$COMM_CACHE/powerline_warning"
 # Only emit this the first time, as it's suprising to the user for the prompt
 # to be replaced, but avoid emitting the warning on subsequent invocations
 if [[ ! -f "$COMM_EMITTED_WARNING" ]]; then
   echo "Default prompt found, attempting to enable powerline" >&2
 
   # Create file to ensure it exists for next time this is run
   mkdir -p "$COMM_CACHE"
   touch "$COMM_EMITTED_WARNING"
 fi
 
 # Check if the powerline fonts are installed
 # If the font is missing then many of the glyphs will render as ?
 # Adapted from https://github.com/powerline/fonts/blob/master/install.sh
 if test "$(uname)" = "Darwin" ; then
   # MacOS
   font_dir="$HOME/Library/Fonts"
 else
   # Linux
   font_dir="${XDG_DATA_HOME:-$HOME/.local/share}/fonts"
   mkdir -p "$font_dir"
 fi
 
 if [[ ! -f "$font_dir/Droid Sans Mono for Powerline.otf" ]]; then
   if [[ ! -d "${powerline_fonts:-/doesnt-exist}" ]]; then
     echo "Unable to determine powerline fonts location" >&2
     return 1
   fi
 
   echo "Installing powerline fonts" >&2
   find "$powerline_fonts" \
     \( -name "*.[ot]tf" -or -name "*.pcf.gz" \) -type f -print0 \
     | xargs -0 -n1 -I % cp "%" "$font_dir/"
 
   if test "$(uname)" = "Darwin" ; then
 
     if [[ "$TERM_PROGRAM" == "Apple_Terminal" ]]; then
       echo "For glyph support, please:
   Select Terminal > Preferences > Text > Font > Change > \
 Select font with 'for Powerline' in the name" >&2
     elif [[ "$TERM_PROGRAM" == "iTerm.app" ]]; then
       echo "For glyph support, please:
   Select iTerm2 > Preferences > Profiles > Text > Font > \
 Select font with 'for Powerline' in the name" >&2
     fi
 
-  elif which fc-cache >/dev/null 2>&1 ; then
+  elif command -v fc-cache ; then
       # Reset font cache on Linux
       echo "Resetting font cache, this may take a moment..." >&2
       fc-cache -f "$font_dir"
   fi
 fi
 
 # shellcheck source=/dev/null
 source "${powerline_root:-.}/share/bash/powerline.sh"