diff --git a/tool/lib/minitest/unit.rb b/tool/lib/minitest/unit.rb
index 7090f8af3f..5d24d0e30d 100644
--- a/tool/lib/minitest/unit.rb
+++ b/tool/lib/minitest/unit.rb
@@ -181,10 +181,12 @@ module MiniTest
     def _assertions= n # :nodoc:
       @_assertions = n
     end
+    alias assertions= _assertions=
 
     def _assertions # :nodoc:
       @_assertions ||= 0
     end
+    alias assertions _assertions
 
     ##
     # Fails unless +test+ is a true value.
diff --git a/tool/test/minitest/test_minitest_unit.rb b/tool/test/minitest/test_minitest_unit.rb
index 1286b15372..5476cf9795 100644
--- a/tool/test/minitest/test_minitest_unit.rb
+++ b/tool/test/minitest/test_minitest_unit.rb
@@ -1372,6 +1372,9 @@ class TestMiniTestUnitTestCase < MiniTest::Unit::TestCase
                   assert_not_same assert_nothing_raised
                   assert_nothing_thrown assert_raise]
 
+    # These are compatibility methods for Minitest 5
+    ignores += %w[assertions assertions=]
+
     asserts = methods.grep(/^assert/).sort - ignores
     refutes = methods.grep(/^refute/).sort - ignores