diff --git a/pyomo/opt/base/solvers.py b/pyomo/opt/base/solvers.py
index c0698165603..4ffef7e7cac 100644
--- a/pyomo/opt/base/solvers.py
+++ b/pyomo/opt/base/solvers.py
@@ -470,8 +470,8 @@ def set_results_format(self, format):
         Set the current results format (if it's valid for the current
         problem format).
         """
-        if (self._problem_format in self._valid_results_formats) and (
-            format in self._valid_results_formats[self._problem_format]
+        if (self._problem_format in self._valid_result_formats) and (
+            format in self._valid_result_formats[self._problem_format]
         ):
             self._results_format = format
         else:
diff --git a/pyomo/opt/tests/base/test_solver.py b/pyomo/opt/tests/base/test_solver.py
index 8ffc647804d..919e9375f60 100644
--- a/pyomo/opt/tests/base/test_solver.py
+++ b/pyomo/opt/tests/base/test_solver.py
@@ -109,7 +109,7 @@ def test_set_problem_format(self):
     def test_set_results_format(self):
         opt = pyomo.opt.SolverFactory("stest1")
         opt._valid_problem_formats = ['a']
-        opt._valid_results_formats = {'a': 'b'}
+        opt._valid_result_formats = {'a': 'b'}
         self.assertEqual(opt.problem_format(), None)
         try:
             opt.set_results_format('b')