diff --git a/solventmapcreator/polynomialanalysis/polynomialvaluecalculator.py b/solventmapcreator/polynomialanalysis/polynomialvaluecalculator.py
index d02cb2e4f87b5a3fa1ee2da0e0fab1ac733e83a5..c247b766e9f7b11ffabba97a8a593cc8e8edf4dc 100644
--- a/solventmapcreator/polynomialanalysis/polynomialvaluecalculator.py
+++ b/solventmapcreator/polynomialanalysis/polynomialvaluecalculator.py
@@ -24,7 +24,11 @@ def calculate_polynomial_values(x_values, polynomial_coefficients):
     was given.
     """
     if type(polynomial_coefficients) is dict:
-        return calculate_poly_value_for_array_from_dict(x_values, polynomial_coefficients)
+        if type(x_values) is float or type(x_values) is np.float64:
+            return calculate_poly_value_from_dict(x_values, polynomial_coefficients)
+        else:
+            return calculate_poly_value_for_array_from_dict(x_values, polynomial_coefficients)
+            
     else:
         return calculate_polynomial_value(x_values, polynomial_coefficients)
 
diff --git a/solventmapcreator/test/polynomialanalysistest/polynomialvaluecalculatortest.py b/solventmapcreator/test/polynomialanalysistest/polynomialvaluecalculatortest.py
index 5035ffba1368f8e6a602c206e7cf12b2aca54973..21cb44aaa5ca8a11680bc1e00ab3788f83ffdbd5 100644
--- a/solventmapcreator/test/polynomialanalysistest/polynomialvaluecalculatortest.py
+++ b/solventmapcreator/test/polynomialanalysistest/polynomialvaluecalculatortest.py
@@ -37,6 +37,9 @@ class PolynomialValueCalculatorTestCase(unittest.TestCase):
         expected_array2 = np.array([4.5, 1.5, 0.5, 1.5, 4.5])
         actual_array2 = polyvalcalc.calculate_polynomial_values(self.input_array, self.poly_coeff_dict["positive"])
         np.testing.assert_array_almost_equal(expected_array2, actual_array2)
+        expected_value = -0.5
+        actual_value = polyvalcalc.calculate_polynomial_values(-1.0, self.poly_coeff_dict)
+        self.assertAlmostEqual(expected_value, actual_value)
     def test_calculate_poly_value_for_array_from_dict(self):
         """Test to see if expected array iss produced.
         """