diff --git a/install_and_cache_pkgs.sh b/install_and_cache_pkgs.sh
index 3ef616d..d85381d 100755
--- a/install_and_cache_pkgs.sh
+++ b/install_and_cache_pkgs.sh
@@ -37,12 +37,14 @@ write_manifest "main" "${manifest_main}" "${cache_dir}/manifest_main.log"
 
 log_empty_line
 
-log "Installing apt-fast for optimized installs..."
-# Install apt-fast for optimized installs.
-/bin/bash -c "$(curl -sL https://git.io/vokNn)"
-log "done"
+if ! apt-fast --version > /dev/null 2>&1; then
+  log "Installing apt-fast for optimized installs..."
+  # Install apt-fast for optimized installs.
+  /bin/bash -c "$(curl -sL https://git.io/vokNn)"
+  log "done"
 
-log_empty_line
+  log_empty_line
+fi
 
 log "Updating APT package list..."
 if [[ -z "$(find -H /var/lib/apt/lists -maxdepth 0 -mmin -5)" ]]; then