diff --git a/lib/acidic_job/workflow.rb b/lib/acidic_job/workflow.rb
index fc62528..e69afac 100644
--- a/lib/acidic_job/workflow.rb
+++ b/lib/acidic_job/workflow.rb
@@ -14,20 +14,20 @@ module Workflow
     def execute_workflow(unique_by:, &block)
       serialized_job = serialize
 
-      AcidicJob.instrument(:define_workflow, **serialized_job) do
-        raise RedefiningWorkflowError if defined? @builder
+      workflow_definition = AcidicJob.instrument(:define_workflow, **serialized_job) do
+        raise RedefiningWorkflowError if defined? @_builder
 
-        @builder = Builder.new
+        @_builder = Builder.new
 
         raise UndefinedWorkflowBlockError unless block_given?
         raise InvalidWorkflowBlockError if block.arity != 1
 
-        block.call @builder
+        block.call @_builder
 
-        raise MissingStepsError if @builder.steps.empty?
+        raise MissingStepsError if @_builder.steps.empty?
 
         # convert the array of steps into a hash of recovery_points and next steps
-        workflow_definition = @builder.define_workflow
+        @_builder.define_workflow
       end
 
       AcidicJob.instrument(:initialize_workflow, "definition" => workflow_definition) do
diff --git a/test/acidic_job/basics_test.rb b/test/acidic_job/basics_test.rb
index 82fe381..a6bd1f9 100644
--- a/test/acidic_job/basics_test.rb
+++ b/test/acidic_job/basics_test.rb
@@ -533,7 +533,7 @@ def step_3; Performance.performed!; end
 
     assert_equal [self.class.name, "Job10"].join("::"), execution.serialized_job["job_class"]
     assert_equal "FINISHED", execution.recover_to
-    assert_equal "a615eeaee21de5179de080de8c3052c8da901138406ba71c38c032845f7d54f4", execution.idempotency_key
+    assert_equal "0ce3d65c09b390b8a53060eb6184a30d4a7025ca403b9f5aeda769932a9e2c86", execution.idempotency_key
 
     assert_equal 6, AcidicJob::Entry.count
     assert_equal(
diff --git a/test/acidic_job/idempotency_key_test.rb b/test/acidic_job/idempotency_key_test.rb
index adbd475..b4381f3 100644
--- a/test/acidic_job/idempotency_key_test.rb
+++ b/test/acidic_job/idempotency_key_test.rb
@@ -46,7 +46,9 @@ def step_1; nil; end
     job = AcidicByArguments.new
     job.perform_now
 
-    assert_equal "4f53cda18c2baa0c0354bb5f9a3ecbe5ed12ab4d8e11ba873c2f11161202b945", job.idempotency_key
+    execution = AcidicJob::Execution.first
+
+    assert_equal "bab619c21aa975baef217fbd5c6e01a7674d9d8ee3fa1c4e2a178e41d7952b23", execution.idempotency_key
   end
 
   test "idempotency_key when unique_by is arguments and arguments are a static string" do
@@ -63,7 +65,9 @@ def step_1; nil; end
     job = AcidicByBlockWithString.new("a")
     job.perform_now
 
-    assert_equal "0eb5b8d6f81bc677da8a08567cc4fa9a06a57e9ec8da85ed73a7f62727996002", job.idempotency_key
+    execution = AcidicJob::Execution.first
+
+    assert_equal "11460654191869f08d979326233f4d4b1287b77ed069c53ac79036d96d54dd3e", execution.idempotency_key
   end
 
   test "idempotency_key when unique_by is arguments and arguments are an array of strings" do
@@ -80,7 +84,9 @@ def step_1; nil; end
     job = AcidicByBlockWithArrayOfStrings.new("a", "b")
     job.perform_now
 
-    assert_equal "0473ef2dc0d324ab659d3580c1134e9d812035905c4781fdd6d529b0c6860e13", job.idempotency_key
+    execution = AcidicJob::Execution.first
+
+    assert_equal "76564b0604a5dfd81d1f637416e664352eda527e2cd78a806e91ad6ccd609eb3", execution.idempotency_key
   end
 
   test "idempotency_key when unique_by is arguments and arguments are an array of different values" do
@@ -97,6 +103,8 @@ def step_1; nil; end
     job = AcidicByBlockWithArgValue.new([1, "string", { a: 1, b: 2 }, [3, 4, 5]])
     job.perform_now
 
-    assert_equal "e493eb3be3e78cb3f40d40402c532efad9cf240d2dd6af839d37ef51a6f71aba", job.idempotency_key
+    execution = AcidicJob::Execution.first
+
+    assert_equal "a7c36d24b42051092df5547146952d4707bf6e04b84774576bad6a37937d018a", execution.idempotency_key
   end
 end