diff --git a/sklearn/gaussian_process/tests/test_kernels.py b/sklearn/gaussian_process/tests/test_kernels.py
index c759f813104a9..a07a406a415dd 100644
--- a/sklearn/gaussian_process/tests/test_kernels.py
+++ b/sklearn/gaussian_process/tests/test_kernels.py
@@ -283,8 +283,9 @@ def test_set_get_params():
         index = 0
         params = kernel.get_params()
         for hyperparameter in kernel.hyperparameters:
-            if hyperparameter.bounds == "fixed":
-                continue
+            if isinstance("string", type(hyperparameter.bounds)):
+                if hyperparameter.bounds == "fixed":
+                    continue
             size = hyperparameter.n_elements
             if size > 1:  # anisotropic kernels
                 assert_almost_equal(np.exp(kernel.theta[index:index + size]),
@@ -298,8 +299,9 @@ def test_set_get_params():
         index = 0
         value = 10  # arbitrary value
         for hyperparameter in kernel.hyperparameters:
-            if hyperparameter.bounds == "fixed":
-                continue
+            if isinstance("string", type(hyperparameter.bounds)):
+                if hyperparameter.bounds == "fixed":
+                    continue
             size = hyperparameter.n_elements
             if size > 1:  # anisotropic kernels
                 kernel.set_params(**{hyperparameter.name: [value] * size})