diff --git a/compiler/src/dotty/tools/dotc/transform/patmat/Space.scala b/compiler/src/dotty/tools/dotc/transform/patmat/Space.scala
index 8e59397189ae..49022cd4cdb4 100644
--- a/compiler/src/dotty/tools/dotc/transform/patmat/Space.scala
+++ b/compiler/src/dotty/tools/dotc/transform/patmat/Space.scala
@@ -323,12 +323,6 @@ class SpaceEngine(using Context) extends SpaceLogic {
 
   private val constantNullType     = ConstantType(Constant(null))
 
-  /** Does the given tree stand for the literal `null`? */
-  def isNullLit(tree: Tree): Boolean = tree match {
-    case Literal(Constant(null)) => true
-    case _ => false
-  }
-
   override def intersectUnrelatedAtomicTypes(tp1: Type, tp2: Type): Space = trace(s"atomic intersection: ${AndType(tp1, tp2).show}", debug) {
     // Precondition: !isSubType(tp1, tp2) && !isSubType(tp2, tp1).
     if !ctx.mode.is(Mode.SafeNulls) && (tp1.isNullType || tp2.isNullType) then
diff --git a/compiler/src/dotty/tools/dotc/typer/Typer.scala b/compiler/src/dotty/tools/dotc/typer/Typer.scala
index 7bf1d1298a5b..4fb5740b2c53 100644
--- a/compiler/src/dotty/tools/dotc/typer/Typer.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Typer.scala
@@ -1581,7 +1581,7 @@ class Typer extends Namer
             result
         }
     }
-    if Nullables.unsafeNullsEnabled then
+    if Nullables.unsafeNullsEnabled && ctx.phase == Phases.typerPhase then
       tree1.putAttachment(Nullables.UnsafeNullsMatch, ())
     tree1
 
diff --git a/compiler/test/dotty/tools/dotc/CompilationTests.scala b/compiler/test/dotty/tools/dotc/CompilationTests.scala
index 4a85d863ed9f..78f99d3b8660 100644
--- a/compiler/test/dotty/tools/dotc/CompilationTests.scala
+++ b/compiler/test/dotty/tools/dotc/CompilationTests.scala
@@ -322,6 +322,7 @@ class CompilationTests {
     aggregateTests(
       compileFilesInDir("tests/explicit-nulls/pos", explicitNullsOptions),
       compileFilesInDir("tests/explicit-nulls/pos-separate", explicitNullsOptions),
+      compileFilesInDir("tests/explicit-nulls/pos-patmat", explicitNullsOptions and "-Xfatal-warnings"),
       compileFilesInDir("tests/explicit-nulls/unsafe-common", explicitNullsOptions and "-language:unsafeNulls"),
     )
   }.checkCompile()
diff --git a/tests/explicit-nulls/neg-patmat/unsafe-match-null-pat.scala b/tests/explicit-nulls/pos-patmat/unsafe-match-null-pat.scala
similarity index 100%
rename from tests/explicit-nulls/neg-patmat/unsafe-match-null-pat.scala
rename to tests/explicit-nulls/pos-patmat/unsafe-match-null-pat.scala