diff --git a/compiler/ast.nim b/compiler/ast.nim
index 2c8f686eb..b8202abe6 100644
--- a/compiler/ast.nim
+++ b/compiler/ast.nim
@@ -1622,7 +1622,7 @@ iterator items*(n: PNode): PNode =
   for i in 0..<n.safeLen: yield n.sons[i]
 
 iterator pairs*(n: PNode): tuple[i: int, n: PNode] =
-  for i in 0..<n.len: yield (i, n.sons[i])
+  for i in 0..<n.safeLen: yield (i, n.sons[i])
 
 proc isAtom*(n: PNode): bool {.inline.} =
   result = n.kind >= nkNone and n.kind <= nkNilLit