diff --git a/compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala b/compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala
index d3545f09b0e7..64c11d190672 100644
--- a/compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala
+++ b/compiler/src/dotty/tools/dotc/printing/PlainPrinter.scala
@@ -211,7 +211,8 @@ class PlainPrinter(_ctx: Context) extends Printer {
           ~ keywordText("erased ").provided(tp.isErasedMethod)
           ~ keywordText("implicit ").provided(tp.isImplicitMethod && !tp.isContextualMethod)
           ~ paramsText(tp)
-          ~ (if tp.resultType.isInstanceOf[MethodType] then ")" else "): ")
+          ~ ")"
+          ~ (Str(": ") provided !tp.resultType.isInstanceOf[MethodOrPoly])
           ~ toText(tp.resultType)
         }
       case tp: ExprType =>
@@ -223,7 +224,7 @@ class PlainPrinter(_ctx: Context) extends Printer {
       case tp: PolyType =>
         changePrec(GlobalPrec) {
           "[" ~ paramsText(tp) ~ "]" ~ lambdaHash(tp) ~
-          (Str(" => ") provided !tp.resultType.isInstanceOf[MethodType]) ~
+          (Str(": ") provided !tp.resultType.isInstanceOf[MethodOrPoly]) ~
           toTextGlobal(tp.resultType)
         }
       case AnnotatedType(tpe, annot) =>
@@ -418,7 +419,7 @@ class PlainPrinter(_ctx: Context) extends Printer {
         (if (isParameter) ": => " else ": ") ~ toTextGlobal(tp.widenExpr)
       case tp: PolyType =>
         "[" ~ paramsText(tp) ~ "]"
-        ~ (Str(": ") provided !tp.resultType.isInstanceOf[MethodType])
+        ~ (Str(": ") provided !tp.resultType.isInstanceOf[MethodOrPoly])
         ~ toTextGlobal(tp.resultType)
       case tp =>
         ": " ~ toTextGlobal(tp)
diff --git a/compiler/test-resources/repl/i5345 b/compiler/test-resources/repl/i5345
index 458aab906978..4cacdf7ae985 100644
--- a/compiler/test-resources/repl/i5345
+++ b/compiler/test-resources/repl/i5345
@@ -1,2 +1,2 @@
 scala>  def x[A, B]: Conversion[A, B] = _ => ???
-def x[A, B] => Conversion[A, B]
+def x[A, B]: Conversion[A, B]
diff --git a/language-server/test/dotty/tools/languageserver/CompletionTest.scala b/language-server/test/dotty/tools/languageserver/CompletionTest.scala
index 1657549f9a7a..c155694c494f 100644
--- a/language-server/test/dotty/tools/languageserver/CompletionTest.scala
+++ b/language-server/test/dotty/tools/languageserver/CompletionTest.scala
@@ -643,7 +643,7 @@ class CompletionTest {
     code"""object Foo
           |extension (foo: Foo.type) def xxxx[A]: Int = 1
           |object Main { Foo.xx${m1} }"""
-      .completion(("xxxx", Method, "[A] => Int"))
+      .completion(("xxxx", Method, "[A]: Int"))
   }
 
   @Test def completeExtensionMethodWithParameterAndTypeParameter: Unit = {
@@ -762,7 +762,7 @@ class CompletionTest {
           |given Baz with {}
           |extension [A](using bar: Bar)(a: A)(using baz: Baz) def xxxx[B]: Either[A, B] = Left(a)
           |object Main { 123.xx${m1} }"""
-      .completion(("xxxx", Method, "(using baz: Baz): [B] => Either[Int, B]"))
+      .completion(("xxxx", Method, "(using baz: Baz)[B]: Either[Int, B]"))
   }
 
   @Test def completeExtensionMethodWithTypeBounds: Unit = {
@@ -772,7 +772,7 @@ class CompletionTest {
           |extension [A >: Bar](a: A) def xxxx[B <: a.type]: Either[A, B] = Left(a)
           |val foo = new Foo {}
           |object Main { foo.xx${m1} }"""
-      .completion(("xxxx", Method, "[B <: (foo : Foo)] => Either[Foo, B]"))
+          .completion(("xxxx", Method, "[B <: (foo : Foo)]: Either[Foo, B]"))
   }
 
   @Test def completeInheritedExtensionMethod: Unit = {
@@ -1034,7 +1034,7 @@ class CompletionTest {
         ("→", Method, "[B](y: B): (A, B)"),
         ("!=", Method, "(x$0: Any): Boolean"),
         ("fromOrdinal", Method, "(ordinal: Int): Foo.Bar"),
-        ("asInstanceOf", Method, "[X0] => X0"),
+        ("asInstanceOf", Method, "[X0]: X0"),
         ("->", Method, "[B](y: B): (A, B)"),
         ("wait", Method, "(x$0: Long, x$1: Int): Unit"),
         ("`back-tick`", Field, "Foo.Bar"),
@@ -1042,7 +1042,7 @@ class CompletionTest {
         ("formatted", Method, "(fmtstr: String): String"),
         ("ensuring", Method, "(cond: A => Boolean, msg: => Any): A"),
         ("wait", Method, "(): Unit"),
-        ("isInstanceOf", Method, "[X0] => Boolean"),
+        ("isInstanceOf", Method, "[X0]: Boolean"),
         ("`match`", Field, "Foo.Bar"),
         ("toString", Method, "(): String"),
         ("ensuring", Method, "(cond: A => Boolean): A"),
diff --git a/tests/neg-custom-args/fatal-warnings/i9408a.check b/tests/neg-custom-args/fatal-warnings/i9408a.check
index f3eceb070113..ce2f8c4edd15 100644
--- a/tests/neg-custom-args/fatal-warnings/i9408a.check
+++ b/tests/neg-custom-args/fatal-warnings/i9408a.check
@@ -9,7 +9,7 @@
 -- Error: tests/neg-custom-args/fatal-warnings/i9408a.scala:26:20 ------------------------------------------------------
 26 |  val length: Int = "qwerty" // error
    |                    ^^^^^^^^
-   |The conversion (Test5.implicitLength : [A] => String => Int) will not be applied implicitly here in Scala 3 because only implicit methods and instances of Conversion class will continue to work as implicit views.
+   |The conversion (Test5.implicitLength : [A]: String => Int) will not be applied implicitly here in Scala 3 because only implicit methods and instances of Conversion class will continue to work as implicit views.
 -- Error: tests/neg-custom-args/fatal-warnings/i9408a.scala:31:20 ------------------------------------------------------
 31 |  val length: Int = "qwerty" // error
    |                    ^^^^^^^^
@@ -21,4 +21,4 @@
 -- Error: tests/neg-custom-args/fatal-warnings/i9408a.scala:59:2 -------------------------------------------------------
 59 |  123.foo // error
    |  ^^^
-   |The conversion (Test11.a2foo : [A] => A => Test11.Foo) will not be applied implicitly here in Scala 3 because only implicit methods and instances of Conversion class will continue to work as implicit views.
+   |The conversion (Test11.a2foo : [A]: A => Test11.Foo) will not be applied implicitly here in Scala 3 because only implicit methods and instances of Conversion class will continue to work as implicit views.