diff --git a/generative/networks/schedulers/ddim.py b/generative/networks/schedulers/ddim.py
index 364cc592..6f2b3bc6 100644
--- a/generative/networks/schedulers/ddim.py
+++ b/generative/networks/schedulers/ddim.py
@@ -104,7 +104,7 @@ def __init__(
 
         # setable values
         self.num_inference_steps = None
-        self.timesteps = torch.from_numpy(np.arange(0, num_train_timesteps)[::-1].copy().astype(np.int64))
+        self.timesteps = torch.from_numpy(np.arange(0, num_train_timesteps)[::-1].astype(np.int64))
 
         self.clip_sample = clip_sample
         self.steps_offset = steps_offset
@@ -117,6 +117,13 @@ def set_timesteps(self, num_inference_steps: int, device: Optional[Union[str, to
             num_inference_steps: number of diffusion steps used when generating samples with a pre-trained model.
             device: target device to put the data.
         """
+        if num_inference_steps > self.num_train_timesteps:
+            raise ValueError(
+                f"`num_inference_steps`: {num_inference_steps} cannot be larger than `self.num_train_timesteps`:"
+                f" {self.num_train_timesteps} as the unet model trained with this scheduler can only handle"
+                f" maximal {self.num_train_timesteps} timesteps."
+            )
+
         self.num_inference_steps = num_inference_steps
         step_ratio = self.num_train_timesteps // self.num_inference_steps
         # creates integer timesteps by multiplying by ratio
diff --git a/generative/networks/schedulers/ddpm.py b/generative/networks/schedulers/ddpm.py
index 9f5ca107..bd4fac29 100644
--- a/generative/networks/schedulers/ddpm.py
+++ b/generative/networks/schedulers/ddpm.py
@@ -102,11 +102,18 @@ def set_timesteps(self, num_inference_steps: int, device: Optional[Union[str, to
             num_inference_steps: number of diffusion steps used when generating samples with a pre-trained model.
             device: target device to put the data.
         """
-        num_inference_steps = min(self.num_train_timesteps, num_inference_steps)
+        if num_inference_steps > self.num_train_timesteps:
+            raise ValueError(
+                f"`num_inference_steps`: {num_inference_steps} cannot be larger than `self.num_train_timesteps`:"
+                f" {self.num_train_timesteps} as the unet model trained with this scheduler can only handle"
+                f" maximal {self.num_train_timesteps} timesteps."
+            )
+
         self.num_inference_steps = num_inference_steps
-        timesteps = np.arange(0, self.num_train_timesteps, self.num_train_timesteps // self.num_inference_steps)[
-            ::-1
-        ].copy()
+        step_ratio = self.num_train_timesteps // self.num_inference_steps
+        # creates integer timesteps by multiplying by ratio
+        # casting to int to avoid issues when num_inference_step is power of 3
+        timesteps = (np.arange(0, num_inference_steps) * step_ratio).round()[::-1].astype(np.int64)
         self.timesteps = torch.from_numpy(timesteps).to(device)
 
     def _get_mean(self, timestep: int, x_0: torch.Tensor, x_t: torch.Tensor) -> torch.Tensor:
diff --git a/generative/networks/schedulers/pndm.py b/generative/networks/schedulers/pndm.py
index 69218f6b..109019d0 100644
--- a/generative/networks/schedulers/pndm.py
+++ b/generative/networks/schedulers/pndm.py
@@ -121,11 +121,18 @@ def set_timesteps(self, num_inference_steps: int, device: Optional[Union[str, to
             num_inference_steps: number of diffusion steps used when generating samples with a pre-trained model.
             device: target device to put the data.
         """
+        if num_inference_steps > self.num_train_timesteps:
+            raise ValueError(
+                f"`num_inference_steps`: {num_inference_steps} cannot be larger than `self.num_train_timesteps`:"
+                f" {self.num_train_timesteps} as the unet model trained with this scheduler can only handle"
+                f" maximal {self.num_train_timesteps} timesteps."
+            )
+
         self.num_inference_steps = num_inference_steps
         step_ratio = self.num_train_timesteps // self.num_inference_steps
         # creates integer timesteps by multiplying by ratio
         # casting to int to avoid issues when num_inference_step is power of 3
-        self._timesteps = (np.arange(0, num_inference_steps) * step_ratio).round()
+        self._timesteps = (np.arange(0, num_inference_steps) * step_ratio).round().astype(np.int64)
         self._timesteps += self.steps_offset
 
         if self.skip_prk_steps:
diff --git a/tests/test_scheduler_ddim.py b/tests/test_scheduler_ddim.py
index 802d85a7..206ae363 100644
--- a/tests/test_scheduler_ddim.py
+++ b/tests/test_scheduler_ddim.py
@@ -57,6 +57,13 @@ def test_set_timesteps(self):
         self.assertEqual(scheduler.num_inference_steps, 100)
         self.assertEqual(len(scheduler.timesteps), 100)
 
+    def test_set_timesteps_with_num_inference_steps_bigger_than_num_train_timesteps(self):
+        scheduler = DDIMScheduler(
+            num_train_timesteps=1000,
+        )
+        with self.assertRaises(ValueError):
+            scheduler.set_timesteps(num_inference_steps=2000)
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/tests/test_scheduler_ddpm.py b/tests/test_scheduler_ddpm.py
index d0f3778c..cb635e31 100644
--- a/tests/test_scheduler_ddpm.py
+++ b/tests/test_scheduler_ddpm.py
@@ -72,6 +72,13 @@ def test_set_timesteps(self):
         self.assertEqual(scheduler.num_inference_steps, 100)
         self.assertEqual(len(scheduler.timesteps), 100)
 
+    def test_set_timesteps_with_num_inference_steps_bigger_than_num_train_timesteps(self):
+        scheduler = DDPMScheduler(
+            num_train_timesteps=1000,
+        )
+        with self.assertRaises(ValueError):
+            scheduler.set_timesteps(num_inference_steps=2000)
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/tests/test_scheduler_pndm.py b/tests/test_scheduler_pndm.py
index 6f30302e..543f692e 100644
--- a/tests/test_scheduler_pndm.py
+++ b/tests/test_scheduler_pndm.py
@@ -67,6 +67,13 @@ def test_set_timesteps_prk(self):
         self.assertEqual(scheduler.num_inference_steps, 109)
         self.assertEqual(len(scheduler.timesteps), 109)
 
+    def test_set_timesteps_with_num_inference_steps_bigger_than_num_train_timesteps(self):
+        scheduler = PNDMScheduler(
+            num_train_timesteps=1000,
+        )
+        with self.assertRaises(ValueError):
+            scheduler.set_timesteps(num_inference_steps=2000)
+
 
 if __name__ == "__main__":
     unittest.main()