diff --git a/compiler/src/dotty/tools/dotc/transform/TreeChecker.scala b/compiler/src/dotty/tools/dotc/transform/TreeChecker.scala
index f84f628fc981..fd8a6992680d 100644
--- a/compiler/src/dotty/tools/dotc/transform/TreeChecker.scala
+++ b/compiler/src/dotty/tools/dotc/transform/TreeChecker.scala
@@ -581,6 +581,14 @@ object TreeChecker {
       super.typedClassDef(cdef, cls)
     }
 
+    override def typedValDef(vdef: untpd.ValDef, sym: Symbol)(using Context): Tree =
+      val tpdTree = super.typedValDef(vdef, sym)
+      vdef.tpt.tpe match
+        case _: ValueType => () // ok
+        case _: ExprType if sym.isOneOf(Param | ParamAccessor) => () // ok
+        case _ => assert(false, i"wrong type, expected a value type for ${sym.fullName}, but found: ${sym.info}")
+      tpdTree
+
     override def typedDefDef(ddef: untpd.DefDef, sym: Symbol)(using Context): Tree =
       def defParamss = ddef.paramss.filter(!_.isEmpty).nestedMap(_.symbol)
       def layout(symss: List[List[Symbol]]): String =
diff --git a/compiler/src/dotty/tools/dotc/typer/Typer.scala b/compiler/src/dotty/tools/dotc/typer/Typer.scala
index 431e863f85d2..bc41fe457ef6 100644
--- a/compiler/src/dotty/tools/dotc/typer/Typer.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Typer.scala
@@ -3242,7 +3242,7 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
     val paramTypes = {
       val hasWildcard = formals.exists(_.existsPart(_.isInstanceOf[WildcardType], StopAt.Static))
       if hasWildcard then formals.map(_ => untpd.TypeTree())
-      else formals.map(untpd.TypeTree)
+      else formals.map(formal => untpd.TypeTree(formal.loBound)) // about loBound, see tests/pos/i18649.scala
     }
 
     val erasedParams = pt match {
diff --git a/tests/pos/i18649.scala b/tests/pos/i18649.scala
new file mode 100644
index 000000000000..d013d5219a1e
--- /dev/null
+++ b/tests/pos/i18649.scala
@@ -0,0 +1,7 @@
+object Test:
+  // always inferred Nothing for `x`
+  def contextFunctionWildcardExplicit: ? ?=> String = x ?=> "foo"
+
+  // used to infer TYPEBOUNDS for the type of the argument
+  def contextFunctionWildcardInserted: ? ?=> String = "foo"
+end Test