diff --git a/src/arachnid/agent.cr b/src/arachnid/agent.cr
index bf4ded2..d7f8002 100644
--- a/src/arachnid/agent.cr
+++ b/src/arachnid/agent.cr
@@ -96,6 +96,9 @@ module Arachnid
       @fetch_delay = fetch_delay || 0
       @history = history || Set(URI).new
       @failures = Set(URI).new
+
+      raise "Cannot have less than 1 fiber" unless fibers.nil? || fibers > 0
+
       @queue = Queue(URI).new(queue, fibers)
 
       @limit = limit
diff --git a/src/arachnid/cli.cr b/src/arachnid/cli.cr
index 7db4bf0..a2b9ed6 100644
--- a/src/arachnid/cli.cr
+++ b/src/arachnid/cli.cr
@@ -8,6 +8,7 @@ module Arachnid
       desc "Arachnid CLI - Simple utilities for scanning the web."
       usage "arachnid [options] [subcommand] [arguments] ..."
       version Arachnid::VERSION
+
       run do |opts, args|
         puts opts.help_string # => help string.
       end
@@ -37,6 +38,7 @@ module Arachnid
         option "-c CODES", "--codes=CODES",   type: Array(Int32), desc: "generate a map of status codes to pages \
                                                                           that responded with that code"
         option "-n", "--limit NUM",           type: Int32,        desc: "maximum number of pages to scan"
+        option "-f", "--fibers NUM",          type: Int32,        desc: "maximum amount of fibers to spin up", default: 10
         option "-o FILE", "--output=FILE",    type: String,       desc: "file to write the report to (if undefined \
                                                                           output will be printed to STDOUT"
 
@@ -72,6 +74,7 @@ module Arachnid
         option "--json",                    type: Bool, desc: "generate the sitemap in JSON format"
         option "-o FILE", "--output=FILE",  type: String, desc: "filename to write the report to. \
                                                                 default is the hostname + .json or .xml"
+        option "-f", "--fibers NUM",          type: Int32,        desc: "maximum amount of fibers to spin up", default: 10
 
         run do |opts, args|
           if args.size != 1
diff --git a/src/arachnid/cli/sitemap.cr b/src/arachnid/cli/sitemap.cr
index 188ff7f..02b2e0b 100644
--- a/src/arachnid/cli/sitemap.cr
+++ b/src/arachnid/cli/sitemap.cr
@@ -15,7 +15,7 @@ module Arachnid
         date = Time.now
         spinner = Spinner::Spinner.new("Wait...")
 
-        spider = Arachnid::Agent.new
+        spider = Arachnid::Agent.new(fibers: opts.fibers)
         spider.visit_urls_like(Regex.new(Regex.escape(url.to_s)))
 
         map = {
diff --git a/src/arachnid/cli/summarize.cr b/src/arachnid/cli/summarize.cr
index 41d93bc..0ff3a03 100644
--- a/src/arachnid/cli/summarize.cr
+++ b/src/arachnid/cli/summarize.cr
@@ -10,7 +10,7 @@ module Arachnid
       def run(opts, urls)
         spinner = Spinner::Spinner.new("Wait...")
 
-        spider = Arachnid::Agent.new(limit: opts.limit)
+        spider = Arachnid::Agent.new(limit: opts.limit, fibers: opts.fibers)
 
         urls.each do |url|
           spider.visit_urls_like(Regex.new(url))