diff --git a/compiler/src/dotty/tools/dotc/typer/ProtoTypes.scala b/compiler/src/dotty/tools/dotc/typer/ProtoTypes.scala
index 2764f6b98707..36e288fbc91a 100644
--- a/compiler/src/dotty/tools/dotc/typer/ProtoTypes.scala
+++ b/compiler/src/dotty/tools/dotc/typer/ProtoTypes.scala
@@ -418,7 +418,7 @@ object ProtoTypes {
 
   /** Create a new TypeVar that represents a dependent method parameter singleton */
   def newDepTypeVar(tp: Type)(implicit ctx: Context): TypeVar =
-    newTypeVar(TypeBounds.upper(AndType(tp, defn.SingletonClass.typeRef)))
+    newTypeVar(TypeBounds.upper(AndType(tp.widenExpr, defn.SingletonClass.typeRef)))
 
   /** The result type of `mt`, where all references to parameters of `mt` are
    *  replaced by either wildcards (if typevarsMissContext) or TypeParamRefs.
diff --git a/tests/neg/i3901.scala b/tests/neg/i3901.scala
new file mode 100644
index 000000000000..8e1451d4628e
--- /dev/null
+++ b/tests/neg/i3901.scala
@@ -0,0 +1,4 @@
+object Crash {
+  def f(cond: => Boolean): cond.type = ???  // error: cond is not stable
+  f(true)
+}