diff --git a/Sources/SortedCollections/BTree/_BTree+Partial RangeReplaceableCollection.swift b/Sources/SortedCollections/BTree/_BTree+Partial RangeReplaceableCollection.swift
index 57eada023..03c6640df 100644
--- a/Sources/SortedCollections/BTree/_BTree+Partial RangeReplaceableCollection.swift	
+++ b/Sources/SortedCollections/BTree/_BTree+Partial RangeReplaceableCollection.swift	
@@ -58,7 +58,7 @@ extension _BTree {
   @inlinable
   @inline(__always)
   public mutating func removeLast(_ k: Int) {
-    assert(0 <= k && k < self.count, "Can't remove more items from a collection than it contains")
+    assert(0 <= k && k <= self.count, "Can't remove more items from a collection than it contains")
     for _ in 0..<k {
       self.removeLast()
     }
@@ -95,7 +95,7 @@ extension _BTree {
   @inlinable
   @inline(__always)
   public mutating func removeFirst(_ k: Int) {
-    assert(0 <= k && k < self.count, "Can't remove more items from a collection than it contains")
+    assert(0 <= k && k <= self.count, "Can't remove more items from a collection than it contains")
     for _ in 0..<k {
       self.removeFirst()
     }
diff --git a/Tests/SortedCollectionsTests/BTree/BTree+Deletion Tests.swift b/Tests/SortedCollectionsTests/BTree/BTree+Deletion Tests.swift
index d2c0adbf3..7d21886ab 100644
--- a/Tests/SortedCollectionsTests/BTree/BTree+Deletion Tests.swift	
+++ b/Tests/SortedCollectionsTests/BTree/BTree+Deletion Tests.swift	
@@ -29,5 +29,29 @@ final class NodeDeletionTests: CollectionTestCase {
       }
     }
   }
+
+  func test_removeAllWithRemoveFirst() {
+    withEvery("size", in: [1, 2, 4, 8, 16, 32, 64, 128, 512]) { size in
+      btreeOfSize(size) { tree, _ in
+        expectEqual(tree.count, size)
+
+        tree.removeFirst(size)
+
+        expectEqual(tree.count, 0)
+      }
+    }
+  }
+
+  func test_removeAllWithRemoveLast() {
+    withEvery("size", in: [1, 2, 4, 8, 16, 32, 64, 128, 512]) { size in
+      btreeOfSize(size) { tree, _ in
+        expectEqual(tree.count, size)
+
+        tree.removeLast(size)
+
+        expectEqual(tree.count, 0)
+      }
+    }
+  }
 }
 #endif