diff --git a/Gemfile.lock b/Gemfile.lock
index 17e5800..9b53a40 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    entitlements-app (1.2.4)
+    entitlements-app (1.2.5)
       concurrent-ruby (~> 1.3, >= 1.3.1)
       dogstatsd-ruby (~> 5.7)
       faraday (~> 2.0)
diff --git a/lib/entitlements.rb b/lib/entitlements.rb
index 21dc118..2be391f 100644
--- a/lib/entitlements.rb
+++ b/lib/entitlements.rb
@@ -22,6 +22,7 @@
 require "ostruct"
 require "resolv"
 require "stringio"
+require "thread"
 require "uri"
 require "yaml"
 
@@ -457,19 +458,33 @@ def self.calculate_actions
     # Calculate old and new membership in each group.
     thread_pool = Concurrent::FixedThreadPool.new(max_parallelism)
     logger.debug("Begin prefetch and validate for all groups")
+
     prep_start = Time.now
-    futures = Entitlements.child_classes.map do |group_name, obj|
-      Concurrent::Future.execute({ executor: thread_pool }) do
-        group_start = Time.now
-        logger.debug("Begin prefetch and validate for #{group_name}")
-        provider = Entitlements.config["groups"].fetch(group_name).fetch("type")
-        timed_operation(phase: "prefetch", provider: provider, target: group_name, concurrent: true) { obj.prefetch }
-        timed_operation(phase: "validate", provider: provider, target: group_name, concurrent: true) { obj.validate }
-        logger.debug("Finished prefetch and validate for #{group_name} in #{Time.now - group_start}")
+    jobs = Entitlements.child_classes
+    completions = Queue.new
+
+    begin
+      jobs.each do |group_name, obj|
+        thread_pool.post do
+          group_start = Time.now
+          logger.debug("Begin prefetch and validate for #{group_name}")
+          provider = Entitlements.config["groups"].fetch(group_name).fetch("type")
+          timed_operation(phase: "prefetch", provider: provider, target: group_name, concurrent: true) { obj.prefetch }
+          timed_operation(phase: "validate", provider: provider, target: group_name, concurrent: true) { obj.validate }
+          logger.debug("Finished prefetch and validate for #{group_name} in #{Time.now - group_start}")
+          completions << nil
+        rescue => e
+          completions << e
+        end
       end
-    end
 
-    futures.each(&:value!)
+      jobs.size.times do
+        exception = completions.pop
+        raise exception if exception
+      end
+    ensure
+      thread_pool.kill
+    end
     logger.debug("Finished all prefetch and validate in #{Time.now - prep_start}")
 
     logger.debug("Begin all calculations")
diff --git a/lib/version.rb b/lib/version.rb
index 6908551..0dd6539 100644
--- a/lib/version.rb
+++ b/lib/version.rb
@@ -2,6 +2,6 @@
 
 module Entitlements
   module Version
-    VERSION = "1.2.4"
+    VERSION = "1.2.5"
   end
 end
diff --git a/spec/unit/entitlements_spec.rb b/spec/unit/entitlements_spec.rb
index cad08fb..9d54a1b 100644
--- a/spec/unit/entitlements_spec.rb
+++ b/spec/unit/entitlements_spec.rb
@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require_relative "spec_helper"
+require "timeout"
 
 describe Entitlements do
   let(:subject) { Entitlements }
@@ -346,6 +347,26 @@
 
       expect(cache[:change_count]).to eq(3)
     end
+
+    it "raises a worker failure without waiting for an earlier job" do
+      Entitlements.config["max_parallelism"] = 2
+      started = Concurrent::Event.new
+      blocker = Concurrent::Event.new
+      allow(Entitlements).to receive(:child_classes)
+        .and_return("ldap-dir" => ldap_controller, "other-ldap-dir" => other_controller)
+      allow(ldap_controller).to receive(:prefetch) do
+        started.set
+        blocker.wait
+      end
+      allow(other_controller).to receive(:prefetch) do
+        started.wait
+        raise "Boom"
+      end
+
+      expect do
+        Timeout.timeout(1) { described_class.calculate }
+      end.to raise_error(RuntimeError, "Boom")
+    end
   end
 
   describe "#execute" do