diff --git a/projects/nerf/nerf/harmonic_embedding.py b/projects/nerf/nerf/harmonic_embedding.py
index 4040eed9..ecd11ce1 100644
--- a/projects/nerf/nerf/harmonic_embedding.py
+++ b/projects/nerf/nerf/harmonic_embedding.py
@@ -69,7 +69,12 @@ class HarmonicEmbedding(torch.nn.Module):
                 dtype=torch.float32,
             )
 
-        self.register_buffer("_frequencies", omega0 * frequencies, persistent=False)
+        try:
+            self.register_buffer("_frequencies", omega0 * frequencies, persistent=False)
+        except TypeError:
+            # workaround for pytorch<1.6
+            self.register_buffer("_frequencies", omega0 * frequencies)
+
         self.include_input = include_input
 
     def forward(self, x: torch.Tensor) -> torch.Tensor:
diff --git a/pytorch3d/renderer/implicit/raysampling.py b/pytorch3d/renderer/implicit/raysampling.py
index 8cb25d76..e3b33958 100644
--- a/pytorch3d/renderer/implicit/raysampling.py
+++ b/pytorch3d/renderer/implicit/raysampling.py
@@ -96,7 +96,10 @@ class GridRaysampler(torch.nn.Module):
             ),
             dim=-1,
         )
-        self.register_buffer("_xy_grid", _xy_grid, persistent=False)
+        try:
+            self.register_buffer("_xy_grid", _xy_grid, persistent=False)
+        except TypeError:
+            self.register_buffer("_xy_grid", _xy_grid)  # workaround for pytorch<1.6
 
     def forward(self, cameras: CamerasBase, **kwargs) -> RayBundle:
         """
diff --git a/tests/test_raysampling.py b/tests/test_raysampling.py
index 766582d7..9c7e3de3 100644
--- a/tests/test_raysampling.py
+++ b/tests/test_raysampling.py
@@ -426,7 +426,10 @@ class TestRaysampling(TestCaseMixin, unittest.TestCase):
             atol=1e-5,
         )
 
-    def test_load_state(self):
+    @unittest.skipIf(
+        torch.__version__[:4] == "1.5.", "non persistent buffer needs PyTorch 1.6"
+    )
+    def test_load_state_different_resolution(self):
         # check that we can load the state of one ray sampler into
         # another with different image size.
         module1 = NDCGridRaysampler(