diff --git a/compiler/lookups.nim b/compiler/lookups.nim
index 9e6da157d6..1ddeeade26 100644
--- a/compiler/lookups.nim
+++ b/compiler/lookups.nim
@@ -604,6 +604,9 @@ proc qualifiedLookUp*(c: PContext, n: PNode, flags: set[TLookupFlag]): PSym =
           result = errorUndeclaredIdentifierHint(c, n[1], ident)
       elif n[1].kind == nkSym:
         result = n[1].sym
+        if result.owner != nil and result.owner != m and checkUndeclared in flags:
+          # dotExpr in templates can end up here
+          result = errorUndeclaredIdentifierHint(c, n[1], considerQuotedIdent(c, n[1]))
       elif checkUndeclared in flags and
            n[1].kind notin {nkOpenSymChoice, nkClosedSymChoice}:
         localError(c.config, n[1].info, "identifier expected, but got: " &
diff --git a/tests/template/t21231.nim b/tests/template/t21231.nim
new file mode 100644
index 0000000000..51e96cdd65
--- /dev/null
+++ b/tests/template/t21231.nim
@@ -0,0 +1,10 @@
+discard """
+  errormsg: "undeclared identifier: 'x'"
+"""
+
+var x: int
+# bug #21231
+template f(y: untyped) = echo y.x
+for i in 1 .. 10:
+  x = i
+  f(system)