diff --git a/src/cmd/compile/internal/noder/irgen.go b/src/cmd/compile/internal/noder/irgen.go
index 64c29435b5..880073a89e 100644
--- a/src/cmd/compile/internal/noder/irgen.go
+++ b/src/cmd/compile/internal/noder/irgen.go
@@ -219,6 +219,10 @@ Outer:
 		}
 	}
 
+	// Check for unusual case where noder2 encounters a type error that types2
+	// doesn't check for (e.g. notinheap incompatibility).
+	base.ExitIfErrors()
+
 	typecheck.DeclareUniverse()
 
 	for _, p := range noders {
diff --git a/src/cmd/compile/internal/noder/transform.go b/src/cmd/compile/internal/noder/transform.go
index e02b7e758d..efbc8f68ce 100644
--- a/src/cmd/compile/internal/noder/transform.go
+++ b/src/cmd/compile/internal/noder/transform.go
@@ -85,7 +85,15 @@ func stringtoruneslit(n *ir.ConvExpr) ir.Node {
 // etc.  Corresponds to typecheck.tcConv.
 func transformConv(n *ir.ConvExpr) ir.Node {
 	t := n.X.Type()
-	op, _ := typecheck.Convertop(n.X.Op() == ir.OLITERAL, t, n.Type())
+	op, why := typecheck.Convertop(n.X.Op() == ir.OLITERAL, t, n.Type())
+	if op == ir.OXXX {
+		// types2 currently ignores pragmas, so a 'notinheap' mismatch is the
+		// one type-related error that it does not catch. This error will be
+		// caught here by Convertop (see two checks near beginning of
+		// Convertop) and reported at the end of noding.
+		base.ErrorfAt(n.Pos(), "cannot convert %L to type %v%s", n.X, n.Type(), why)
+		return n
+	}
 	n.SetOp(op)
 	switch n.Op() {
 	case ir.OCONVNOP:
diff --git a/test/run.go b/test/run.go
index 90861786df..d6209c2591 100644
--- a/test/run.go
+++ b/test/run.go
@@ -2204,8 +2204,7 @@ var g3Failures = setOf(
 
 	"typeparam/nested.go", // -G=3 doesn't support function-local types with generics
 
-	"typeparam/mdempsky/4.go",  // -G=3 can't export functions with labeled breaks in loops
-	"typeparam/mdempsky/11.go", // types2/noder2 should give conversion error, because of "notinheap" mismatch
+	"typeparam/mdempsky/4.go", // -G=3 can't export functions with labeled breaks in loops
 )
 
 var unifiedFailures = setOf(