diff --git a/compiler/semexprs.nim b/compiler/semexprs.nim
index 2efa1259a890a..8ac8f47508b6a 100644
--- a/compiler/semexprs.nim
+++ b/compiler/semexprs.nim
@@ -319,6 +319,8 @@ proc semConv(c: PContext, n: PNode; expectedType: PType = nil): PNode =
       return evaluated
     else:
       targetType = targetType.base
+  of tyAnything, tyUntyped, tyTyped:
+    localError(c.config, n.info, "illegal type conversion to '$1'" % typeToString(targetType))
   else: discard
 
   maybeLiftType(targetType, c, n[0].info)
diff --git a/tests/arc/t20588.nim b/tests/arc/t20588.nim
new file mode 100644
index 0000000000000..d747c656d369d
--- /dev/null
+++ b/tests/arc/t20588.nim
@@ -0,0 +1,22 @@
+discard """
+  cmd: "nim check --warnings:off --hints:off $file"
+  errormsg: ""
+  nimout: '''
+t20588.nim(20, 12) Error: illegal type conversion to 'auto'
+t20588.nim(21, 14) Error: illegal type conversion to 'typed'
+t20588.nim(22, 16) Error: illegal type conversion to 'untyped'
+'''
+"""
+
+
+
+
+
+
+
+
+
+
+discard 0.0.auto
+discard typed("abc")
+discard untyped(4)