diff --git a/Library/Homebrew/test/utils/popen_spec.rb b/Library/Homebrew/test/utils/popen_spec.rb
index ff4f366a7c..9dcac24180 100644
--- a/Library/Homebrew/test/utils/popen_spec.rb
+++ b/Library/Homebrew/test/utils/popen_spec.rb
@@ -75,12 +75,12 @@ describe Utils do
 
   describe "::safe_popen_read" do
     it "does not raise an error if the command succeeds" do
-      expect(subject.safe_popen_read("sh", "-c", "true")).to eq("")
+      expect(described_class.safe_popen_read("sh", "-c", "true")).to eq("")
       expect($CHILD_STATUS).to be_a_success
     end
 
     it "raises an error if the command fails" do
-      expect { subject.safe_popen_read("sh", "-c", "false") }.to raise_error(ErrorDuringExecution)
+      expect { described_class.safe_popen_read("sh", "-c", "false") }.to raise_error(ErrorDuringExecution)
       expect($CHILD_STATUS).to be_a_failure
     end
   end
@@ -88,14 +88,14 @@ describe Utils do
   describe "::safe_popen_write" do
     it "does not raise an error if the command succeeds" do
       expect(
-        subject.safe_popen_write("grep", "success") { |pipe| pipe.write "success\n" }.chomp,
+        described_class.safe_popen_write("grep", "success") { |pipe| pipe.write "success\n" }.chomp,
       ).to eq("success")
       expect($CHILD_STATUS).to be_a_success
     end
 
     it "raises an error if the command fails" do
       expect {
-        subject.safe_popen_write("grep", "success") { |pipe| pipe.write "failure\n" }
+        described_class.safe_popen_write("grep", "success") { |pipe| pipe.write "failure\n" }
       }.to raise_error(ErrorDuringExecution)
       expect($CHILD_STATUS).to be_a_failure
     end