diff --git a/compiler/src/dotty/tools/dotc/typer/Applications.scala b/compiler/src/dotty/tools/dotc/typer/Applications.scala
index 48a5738b4074..7961f74035e8 100644
--- a/compiler/src/dotty/tools/dotc/typer/Applications.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Applications.scala
@@ -635,15 +635,16 @@ trait Applications extends Compatibility {
         // matches expected type
         false
       case argtpe =>
-        def SAMargOK = formal match {
-          case SAMType(sam) => argtpe <:< sam.toFunctionType(isJava = formal.classSymbol.is(JavaDefined))
-          case _ => false
-        }
+        def SAMargOK(onlyFunctionalInterface: Boolean) =
+          (!onlyFunctionalInterface || formal.classSymbol.hasAnnotation(defn.FunctionalInterfaceAnnot))
+          && formal.match
+            case SAMType(sam) => argtpe <:< sam.toFunctionType(isJava = formal.classSymbol.is(JavaDefined))
+            case _ => false
         if argMatch == ArgMatch.SubType then
-          argtpe relaxed_<:< formal.widenExpr
+          (argtpe relaxed_<:< formal.widenExpr) || SAMargOK(onlyFunctionalInterface = true)
         else
           isCompatible(argtpe, formal)
-          || ctx.mode.is(Mode.ImplicitsEnabled) && SAMargOK
+          || ctx.mode.is(Mode.ImplicitsEnabled) && SAMargOK(onlyFunctionalInterface = false)
           || argMatch == ArgMatch.CompatibleCAP
               && {
                 val argtpe1 = argtpe.widen
@@ -1877,12 +1878,12 @@ trait Applications extends Compatibility {
 
         record("resolveOverloaded.FunProto", alts.length)
         val alts1 = narrowBySize(alts)
-        //report.log(i"narrowed by size: ${alts1.map(_.symbol.showDcl)}%, %")
+        overload.println(i"narrowed by size: ${alts1.map(_.symbol.showDcl)}%, %")
         if isDetermined(alts1) then alts1
         else
           record("resolveOverloaded.narrowedBySize", alts1.length)
           val alts2 = narrowByShapes(alts1)
-          //report.log(i"narrowed by shape: ${alts2.map(_.symbol.showDcl)}%, %")
+          overload.println(i"narrowed by shape: ${alts2.map(_.symbol.showDcl)}%, %")
           if isDetermined(alts2) then alts2
           else
             record("resolveOverloaded.narrowedByShape", alts2.length)
diff --git a/tests/neg/i11899.scala b/tests/neg/i11899.scala
new file mode 100644
index 000000000000..3ae8fc496bfa
--- /dev/null
+++ b/tests/neg/i11899.scala
@@ -0,0 +1,10 @@
+import java.util.function.Function
+
+class Future[T](val initial: T) {
+  def map[V](v: V): Unit = println(v)
+  def map[U](fn: Function[T, U]): Unit = println(fn(initial))
+}
+
+val f = new Future(42)
+val fn = (i: Int) => i.toString
+def test = f.map(fn)  // error
diff --git a/tests/run/i11938.scala b/tests/run/i11938.scala
new file mode 100644
index 000000000000..1f8acd7fc2fc
--- /dev/null
+++ b/tests/run/i11938.scala
@@ -0,0 +1,15 @@
+import java.util.function.Function
+
+class Future[T](val initial: T) {
+  def map[V](v: V): Unit = println(v)
+  //def map(v: String): Unit = println(v)
+  def map[U](fn: Function[T, U]): Unit = println(fn(initial))
+}
+
+object Test {
+  val f = new Future(42)
+  def fn(i: Int) = i.toString
+  def main(args: Array[String]): Unit =
+    f.map((i: Int) => i.toString)
+    f.map(fn)
+}
\ No newline at end of file