diff --git a/lib/pure/collections/sequtils.nim b/lib/pure/collections/sequtils.nim
index 63d910a8edc4e..2e21786bbd169 100644
--- a/lib/pure/collections/sequtils.nim
+++ b/lib/pure/collections/sequtils.nim
@@ -709,7 +709,7 @@ template applyIt*(varSeq, op: untyped) =
   ##   var nums = @[1, 2, 3, 4]
   ##   nums.applyIt(it * 3)
   ##   assert nums[0] + nums[3] == 15
-  for i in 0 ..< varSeq.len:
+  for i in low(varSeq) .. high(varSeq):
     let it {.inject.} = varSeq[i]
     varSeq[i] = op