diff --git a/Library/Homebrew/test/cmd/install_spec.rb b/Library/Homebrew/test/cmd/install_spec.rb
index c7a4bba552..c3aef27000 100644
--- a/Library/Homebrew/test/cmd/install_spec.rb
+++ b/Library/Homebrew/test/cmd/install_spec.rb
@@ -45,7 +45,7 @@ describe "brew install" do
     repo_path.join("bin").mkpath
 
     repo_path.cd do
-      system "git", "init"
+      system "git", "-c", "init.defaultBranch=master", "init"
       system "git", "remote", "add", "origin", "https://github.com/Homebrew/homebrew-foo"
       FileUtils.touch "bin/something.bin"
       FileUtils.touch "README"
diff --git a/Library/Homebrew/test/dev-cmd/audit_spec.rb b/Library/Homebrew/test/dev-cmd/audit_spec.rb
index f05566a10e..56031ac601 100644
--- a/Library/Homebrew/test/dev-cmd/audit_spec.rb
+++ b/Library/Homebrew/test/dev-cmd/audit_spec.rb
@@ -927,7 +927,7 @@ module Homebrew
 
         tap_path.cd do
           system "git", "fetch"
-          system "git", "reset", "--hard", "origin/master"
+          system "git", "reset", "--hard", "origin/HEAD"
         end
       end
 
diff --git a/Library/Homebrew/test/dev-cmd/bottle_spec.rb b/Library/Homebrew/test/dev-cmd/bottle_spec.rb
index 476cd816da..6c4f5510fc 100644
--- a/Library/Homebrew/test/dev-cmd/bottle_spec.rb
+++ b/Library/Homebrew/test/dev-cmd/bottle_spec.rb
@@ -80,7 +80,7 @@ describe "brew bottle" do
 
     it "adds the bottle block to a formula that has none" do
       core_tap.path.cd do
-        system "git", "init"
+        system "git", "-c", "init.defaultBranch=master", "init"
         setup_test_formula "testball"
         system "git", "add", "--all"
         system "git", "commit", "-m", "testball 0.1"
@@ -140,7 +140,7 @@ describe "brew bottle" do
 
     it "replaces the bottle block in a formula that already has a bottle block" do
       core_tap.path.cd do
-        system "git", "init"
+        system "git", "-c", "init.defaultBranch=master", "init"
         setup_test_formula "testball", bottle_block: <<~EOS
 
           bottle do
@@ -207,7 +207,7 @@ describe "brew bottle" do
 
     it "updates the bottle block in a formula that already has a bottle block when using --keep-old" do
       core_tap.path.cd do
-        system "git", "init"
+        system "git", "-c", "init.defaultBranch=master", "init"
         setup_test_formula "testball", bottle_block: <<~EOS
 
           bottle do
diff --git a/Library/Homebrew/test/download_strategies/git_spec.rb b/Library/Homebrew/test/download_strategies/git_spec.rb
index a9d8e6215b..eb7010669a 100644
--- a/Library/Homebrew/test/download_strategies/git_spec.rb
+++ b/Library/Homebrew/test/download_strategies/git_spec.rb
@@ -23,7 +23,7 @@ describe GitDownloadStrategy do
   end
 
   def setup_git_repo
-    system "git", "init"
+    system "git", "-c", "init.defaultBranch=master", "init"
     system "git", "remote", "add", "origin", "https://github.com/Homebrew/homebrew-foo"
     FileUtils.touch "README"
     git_commit_all
diff --git a/Library/Homebrew/test/formula_spec.rb b/Library/Homebrew/test/formula_spec.rb
index 6aeb223eff..6c8a74c93c 100644
--- a/Library/Homebrew/test/formula_spec.rb
+++ b/Library/Homebrew/test/formula_spec.rb
@@ -1480,7 +1480,7 @@ describe Formula do
         testball_repo.cd do
           FileUtils.touch "LICENSE"
 
-          system("git", "init")
+          system("git", "-c", "init.defaultBranch=master", "init")
           system("git", "add", "--all")
           system("git", "commit", "-m", "Initial commit")
         end