diff --git a/Cargo.toml b/Cargo.toml
index 2bc16881..c0d56191 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -36,7 +36,7 @@ keywords = [
 license = "MIT"
 readme = "README.md"
 repository = "https://github.com/ferrilab/bitvec"
-rust-version = "1.56"
+rust-version = "1.81"
 
 [features]
 alloc = [
diff --git a/src/vec/iter.rs b/src/vec/iter.rs
index afa3848a..ff891920 100644
--- a/src/vec/iter.rs
+++ b/src/vec/iter.rs
@@ -540,8 +540,9 @@ where
 #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
 enum FillStatus {
 	/// The drain span is completely filled.
+	/// Note in this case, the replacement source may or may not be exhausted.
 	FullSpan   = 0,
-	/// The replacement source is completely exhausted.
+	/// The replacement source is completely exhausted, but the drain span is not filled yet.
 	EmptyInput = 1,
 }
 
@@ -682,7 +683,7 @@ where
 				self.drain.move_tail(len);
 			}
 			let filled = self.drain.fill(collected.by_ref());
-			debug_assert_eq!(filled, FillStatus::EmptyInput);
+			debug_assert_eq!(filled, FillStatus::FullSpan);
 			debug_assert_eq!(collected.len(), 0);
 		}
 	}
diff --git a/src/vec/tests/iter.rs b/src/vec/tests/iter.rs
index 217f5337..0eaabafe 100644
--- a/src/vec/tests/iter.rs
+++ b/src/vec/tests/iter.rs
@@ -38,4 +38,13 @@ fn splice() {
 	let mut bv = bitvec![0, 1, 0, 0, 1];
 	drop(bv.splice(2 .. 2, Some(true)));
 	assert_eq!(bv, bits![0, 1, 1, 0, 0, 1]);
+
+	let mut bv = bitvec![0, 1, 0, 0, 1];
+	drop(bv.splice(
+		2 .. 2,
+		(0usize .. 2).flat_map(|index| {
+			let array = BitArray::<_, Lsb0>::from(index);
+			array.into_iter().take(2)
+		}),
+	));
 }