diff --git a/mosdef_dihedral_fit/dihedral_fit/fit_dihedral_with_gomc.py b/mosdef_dihedral_fit/dihedral_fit/fit_dihedral_with_gomc.py
index 9ad79a7..8067f63 100755
--- a/mosdef_dihedral_fit/dihedral_fit/fit_dihedral_with_gomc.py
+++ b/mosdef_dihedral_fit/dihedral_fit/fit_dihedral_with_gomc.py
@@ -286,7 +286,7 @@ def fit_dihedral_with_gomc(
 
         NOTE: This value may need adjusted to get the dihedral fit to solve correctly.
 
-    fit_validation_r_squared_rtol: float>0, default=2.5e-02
+    fit_validation_r_squared_rtol: float (0 < fit_min_validated_r_squared < 1), default=2.5e-02
         Where the QM data is defined as the actual data; this is the difference
         of the dihedral's calculated R-squared values between:
         * The QM-MM fitting process, where the fit MM dihedral k-values are zero (0).
@@ -622,20 +622,20 @@ def fit_dihedral_with_gomc(
     else:
         raise TypeError(
             f"ERROR: The 'fit_min_validated_r_squared' is a {type(fit_min_validated_r_squared)}, "
-            f"but it must be a float."
+            f"but it must be a 0<float<1."
         )
 
     # test the 'fit_validation_r_squared_rtol' input
     if isinstance(fit_validation_r_squared_rtol, float):
-        if not fit_validation_r_squared_rtol > 0 :
+        if not (fit_validation_r_squared_rtol>0 and fit_validation_r_squared_rtol<1):
             raise ValueError(
                 f"ERROR: The 'fit_validation_r_squared_rtol' = {fit_validation_r_squared_rtol}, "
-                f"but it must be a float>0.")
+                f"but it must be a 0<float<1.")
 
     else:
         raise TypeError(
             f"ERROR: The 'fit_validation_r_squared_rtol' is a {type( fit_validation_r_squared_rtol)}, "
-            f"but it must be a float."
+            f"but it must be a 0<float<1."
         )
 
     # test the 'gomc_cpu_cores' input
diff --git a/mosdef_dihedral_fit/tests/test_fit_dihedral_with_gomc.py b/mosdef_dihedral_fit/tests/test_fit_dihedral_with_gomc.py
index 863658b..4829fb2 100644
--- a/mosdef_dihedral_fit/tests/test_fit_dihedral_with_gomc.py
+++ b/mosdef_dihedral_fit/tests/test_fit_dihedral_with_gomc.py
@@ -3927,7 +3927,7 @@ def test_fit_min_validated_r_squared_not_a_float(self):
         with pytest.raises(
                 TypeError,
                 match=f"ERROR: The 'fit_min_validated_r_squared' is a {type(2)}, "
-                      f"but it must be a float."
+                      f"but it must be a 0<float<1."
         ):
             fit_dihedral_with_gomc(
                 ['CT', 'CT', 'C', 'OH'],
@@ -3954,7 +3954,7 @@ def test_fit_validation_r_squared_rtol_not_correct_value_is_0(self):
         with pytest.raises(
                 ValueError,
                 match=f"ERROR: The 'fit_validation_r_squared_rtol' = {0.00}, "
-                      f"but it must be a float>0"
+                      f"but it must be a 0<float<1."
         ):
             fit_dihedral_with_gomc(
                 ['CT', 'CT', 'C', 'OH'],
@@ -3980,8 +3980,8 @@ def test_fit_validation_r_squared_rtol_not_correct_value_is_0(self):
     def test_fit_validation_r_squared_rtol_not_correct_value_is_1(self):
         with pytest.raises(
                 ValueError,
-                match=f"ERROR: The 'fit_validation_r_squared_rtol' = {-1.00}, "
-                      f"but it must be a float>0."
+                match=f"ERROR: The 'fit_validation_r_squared_rtol' = {1.00}, "
+                      f"but it must be a 0<float<1."
         ):
             fit_dihedral_with_gomc(
                 ['CT', 'CT', 'C', 'OH'],
@@ -4001,14 +4001,14 @@ def test_fit_validation_r_squared_rtol_not_correct_value_is_1(self):
                 atom_type_naming_style='general',
                 gomc_cpu_cores=1,
                 fit_min_validated_r_squared=0.99,
-                fit_validation_r_squared_rtol=-1.00
+                fit_validation_r_squared_rtol=1.00
             )
 
     def test_fit_validation_r_squared_rtol_not_a_float(self):
         with pytest.raises(
                 TypeError,
                 match=f"ERROR: The 'fit_validation_r_squared_rtol' is a {type(2)}, "
-                      f"but it must be a float."
+                      f"but it must be a 0<float<1."
         ):
             fit_dihedral_with_gomc(
                 ['CT', 'CT', 'C', 'OH'],