diff --git a/spec/cztop/actor_spec.rb b/spec/cztop/actor_spec.rb
index <HASH>..<HASH> 100644
--- a/spec/cztop/actor_spec.rb
+++ b/spec/cztop/actor_spec.rb
@@ -252,7 +252,7 @@ describe CZTop::Actor do
     context "threads" do
       let(:mutex) { actor.instance_variable_get(:@mtx) }
       it "is thread-safe" do
-        expect(mutex).to receive(:synchronize).at_least(1)
+        expect(mutex).to receive(:synchronize).at_least(:once)
           .and_call_original
         actor << "foo"
       end
@@ -320,7 +320,7 @@ describe CZTop::Actor do
     context "threads" do
       let(:mutex) { actor.instance_variable_get(:@mtx) }
       it "is thread-safe" do
-        expect(mutex).to receive(:synchronize).at_least(1)
+        expect(mutex).to receive(:synchronize).at_least(:once)
           .and_call_original
         actor << "foo"
         actor.receive
@@ -365,7 +365,7 @@ describe CZTop::Actor do
     context "threads" do
       let(:mutex) { actor.instance_variable_get(:@mtx) }
       it "is thread-safe" do
-        expect(mutex).to receive(:synchronize).at_least(1)
+        expect(mutex).to receive(:synchronize).at_least(:once)
           .and_call_original
         response
       end
do it like it says in the rspec-mocks README

The README says it'll need a call to #times if given as integer. I don't
care. I hate the RSpec syntax anyway.