diff --git a/src/tensor/index.rs b/src/tensor/index.rs
index d8ad2fa5..2bed7772 100644
--- a/src/tensor/index.rs
+++ b/src/tensor/index.rs
@@ -52,7 +52,7 @@
 //! shape mismatch error due to advanced indexing rule. Another distinction
 //! is that `i` guarantees the input and result tensor shares the same
 //! underlying storage, while NumPy may copy the tensor in certain scenarios.
-use crate::{TchError, Tensor};
+use crate::{Result, TchError, Tensor};
 use std::ops::{
     Bound, Range, RangeBounds, RangeFrom, RangeFull, RangeInclusive, RangeTo, RangeToInclusive,
 };
@@ -133,6 +133,7 @@ impl_from_range!(RangeToInclusive<i64>);
 
 pub trait IndexOp<T> {
     fn i(&self, index: T) -> Tensor;
+    fn f_i(&self, index: T) -> Result<Tensor>;
 }
 
 impl<A> IndexOp<A> for Tensor
@@ -140,7 +141,11 @@ where
     A: Into<TensorIndexer>,
 {
     fn i(&self, index: A) -> Tensor {
-        self.indexer(&[index.into()])
+        self.f_i(index).unwrap()
+    }
+
+    fn f_i(&self, index: A) -> Result<Tensor> {
+        self.f_indexer(&[index.into()])
     }
 }
 
@@ -149,8 +154,12 @@ where
     A: Into<TensorIndexer>,
 {
     fn i(&self, index: (A,)) -> Tensor {
+        self.f_i(index).unwrap()
+    }
+
+    fn f_i(&self, index: (A,)) -> Result<Tensor> {
         let idx_a = index.0.into();
-        self.indexer(&[idx_a])
+        self.f_indexer(&[idx_a])
     }
 }
 
@@ -160,9 +169,13 @@ where
     B: Into<TensorIndexer>,
 {
     fn i(&self, index: (A, B)) -> Tensor {
+        self.f_i(index).unwrap()
+    }
+
+    fn f_i(&self, index: (A, B)) -> Result<Tensor> {
         let idx_a = index.0.into();
         let idx_b = index.1.into();
-        self.indexer(&[idx_a, idx_b])
+        self.f_indexer(&[idx_a, idx_b])
     }
 }
 
@@ -173,10 +186,14 @@ where
     C: Into<TensorIndexer>,
 {
     fn i(&self, index: (A, B, C)) -> Tensor {
+        self.f_i(index).unwrap()
+    }
+
+    fn f_i(&self, index: (A, B, C)) -> Result<Tensor> {
         let idx_a = index.0.into();
         let idx_b = index.1.into();
         let idx_c = index.2.into();
-        self.indexer(&[idx_a, idx_b, idx_c])
+        self.f_indexer(&[idx_a, idx_b, idx_c])
     }
 }
 
@@ -188,11 +205,15 @@ where
     D: Into<TensorIndexer>,
 {
     fn i(&self, index: (A, B, C, D)) -> Tensor {
+        self.f_i(index).unwrap()
+    }
+
+    fn f_i(&self, index: (A, B, C, D)) -> Result<Tensor> {
         let idx_a = index.0.into();
         let idx_b = index.1.into();
         let idx_c = index.2.into();
         let idx_d = index.3.into();
-        self.indexer(&[idx_a, idx_b, idx_c, idx_d])
+        self.f_indexer(&[idx_a, idx_b, idx_c, idx_d])
     }
 }
 
@@ -205,12 +226,16 @@ where
     E: Into<TensorIndexer>,
 {
     fn i(&self, index: (A, B, C, D, E)) -> Tensor {
+        self.f_i(index).unwrap()
+    }
+
+    fn f_i(&self, index: (A, B, C, D, E)) -> Result<Tensor> {
         let idx_a = index.0.into();
         let idx_b = index.1.into();
         let idx_c = index.2.into();
         let idx_d = index.3.into();
         let idx_e = index.4.into();
-        self.indexer(&[idx_a, idx_b, idx_c, idx_d, idx_e])
+        self.f_indexer(&[idx_a, idx_b, idx_c, idx_d, idx_e])
     }
 }
 
@@ -224,13 +249,17 @@ where
     F: Into<TensorIndexer>,
 {
     fn i(&self, index: (A, B, C, D, E, F)) -> Tensor {
+        self.f_i(index).unwrap()
+    }
+
+    fn f_i(&self, index: (A, B, C, D, E, F)) -> Result<Tensor> {
         let idx_a = index.0.into();
         let idx_b = index.1.into();
         let idx_c = index.2.into();
         let idx_d = index.3.into();
         let idx_e = index.4.into();
         let idx_f = index.5.into();
-        self.indexer(&[idx_a, idx_b, idx_c, idx_d, idx_e, idx_f])
+        self.f_indexer(&[idx_a, idx_b, idx_c, idx_d, idx_e, idx_f])
     }
 }
 
@@ -245,6 +274,10 @@ where
     G: Into<TensorIndexer>,
 {
     fn i(&self, index: (A, B, C, D, E, F, G)) -> Tensor {
+        self.f_i(index).unwrap()
+    }
+
+    fn f_i(&self, index: (A, B, C, D, E, F, G)) -> Result<Tensor> {
         let idx_a = index.0.into();
         let idx_b = index.1.into();
         let idx_c = index.2.into();
@@ -252,12 +285,12 @@ where
         let idx_e = index.4.into();
         let idx_f = index.5.into();
         let idx_g = index.6.into();
-        self.indexer(&[idx_a, idx_b, idx_c, idx_d, idx_e, idx_f, idx_g])
+        self.f_indexer(&[idx_a, idx_b, idx_c, idx_d, idx_e, idx_f, idx_g])
     }
 }
 
 impl Tensor {
-    fn f_indexer(&self, index_spec: &[TensorIndexer]) -> Result<Tensor, TchError> {
+    fn f_indexer(&self, index_spec: &[TensorIndexer]) -> Result<Tensor> {
         use std::ops::Bound::*;
         use TensorIndexer::*;
 
@@ -321,7 +354,7 @@ impl Tensor {
                         (Excluded(start), Included(end)) => Some((*start + 1, *end - *start)),
                         (Excluded(start), Excluded(end)) => Some((*start + 1, *end - *start - 1)),
                     } {
-                        (curr_tensor.narrow(curr_idx, start, length.max(0)), curr_idx + 1)
+                        (curr_tensor.f_narrow(curr_idx, start, length.max(0))?, curr_idx + 1)
                     } else {
                         (curr_tensor, curr_idx + 1)
                     }
@@ -331,15 +364,9 @@ impl Tensor {
                     (curr_tensor.index_select(curr_idx, &index_tensor), curr_idx + 1)
                 }
             };
-
             curr_tensor = next_tensor;
             curr_idx = next_idx;
         }
-
         Ok(curr_tensor)
     }
-
-    fn indexer(&self, index_spec: &[TensorIndexer]) -> Tensor {
-        self.f_indexer(index_spec).unwrap()
-    }
 }
diff --git a/tests/tensor_tests.rs b/tests/tensor_tests.rs
index 1da8b1db..fc8e585a 100644
--- a/tests/tensor_tests.rs
+++ b/tests/tensor_tests.rs
@@ -1,3 +1,4 @@
+#![allow(clippy::unnecessary_fallible_conversions)]
 use anyhow::Result;
 use half::f16;
 use std::convert::{TryFrom, TryInto};