diff --git a/compiler/transf.nim b/compiler/transf.nim
index 3db861481a7f..bd1a9cc4ca1f 100644
--- a/compiler/transf.nim
+++ b/compiler/transf.nim
@@ -637,6 +637,12 @@ proc putArgInto(arg: PNode, formal: PType): TPutArgInto =
     case arg.kind
     of nkStmtListExpr:
       return paComplexOpenarray
+    of nkCall:
+      if skipTypes(arg.typ, abstractInst).kind in {tyOpenArray, tyVarargs}:
+        # XXX incorrect, causes #13417 when `arg` has side effects.
+        return paDirectMapping
+      else:
+        return paComplexOpenarray
     of nkBracket:
       return paFastAsgnTakeTypeFromArg
     else:
@@ -803,7 +809,7 @@ proc transformFor(c: PTransf, n: PNode): PNode =
       stmtList.add(newAsgnStmt(c, nkFastAsgn, temp, addrExp, true))
       newC.mapping[formal.itemId] = newDeref(temp)
     of paComplexOpenarray:
-      # arrays will deep copy here (pretty bad).
+      # XXX arrays will deep copy here (pretty bad).
       var temp = newTemp(c, arg.typ, formal.info)
       addVar(v, temp)
       stmtList.add(newAsgnStmt(c, nkFastAsgn, temp, arg, true))
diff --git a/tests/iter/titeropenarray.nim b/tests/iter/titeropenarray.nim
new file mode 100644
index 000000000000..918195b16168
--- /dev/null
+++ b/tests/iter/titeropenarray.nim
@@ -0,0 +1,32 @@
+block: # issue #13417
+  var s: seq[int] = @[]
+  proc p1(): seq[int] =
+    s.add(3)
+    @[1,2]
+
+  iterator ip1(v: openArray[int]): auto =
+    for x in v:
+      yield x
+
+  for x in ip1(p1()):
+    s.add(x)
+
+  doAssert s == @[3, 1, 2]
+
+import std / sequtils
+
+block: # issue #19703
+  iterator combinations[T](s: seq[T], r: Positive): seq[T] =
+    yield @[s[0], s[1]]
+
+  iterator pairwise[T](s: openArray[T]): seq[T] =
+    yield @[s[0], s[0]]
+
+  proc checkSpecialSubset5(s: seq[int]): bool =
+    toSeq(
+      toSeq(
+        s.combinations(2)
+      ).map(proc(a: auto): int = a[0]).pairwise()
+    ).any(proc(a: auto): bool = a == @[s[0], s[0]])
+
+  doAssert checkSpecialSubset5 @[1, 2]