diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Flow.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Flow.java
index 29ab8435ada..df28548152a 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Flow.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Flow.java
@@ -910,7 +910,7 @@ public class Flow {
                     Set<PatternDescription> toAdd = new HashSet<>();
 
                     for (Type sup : types.directSupertypes(bpOne.type)) {
-                        ClassSymbol clazz = (ClassSymbol) sup.tsym;
+                        ClassSymbol clazz = (ClassSymbol) types.erasure(sup).tsym;
 
                         clazz.complete();
 
diff --git a/test/langtools/tools/javac/patterns/T8340145.java b/test/langtools/tools/javac/patterns/T8340145.java
new file mode 100644
index 00000000000..04b12664b72
--- /dev/null
+++ b/test/langtools/tools/javac/patterns/T8340145.java
@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8340145
+ * @summary Problem with generic pattern matching results in internal compiler error
+ * @compile T8340145.java
+ * @run main T8340145
+ */
+public class T8340145 {
+    public static void main(String[] args) {
+        Option<Integer> optionInteger = new Option.Some<>(21);
+        Number number = Option.unwrapOrElse(optionInteger, 5.2);
+
+        Option2<Impl> optionBound = new Option2.Some<>(new Impl (){});
+        Bound number2 = Option2.unwrapOrElse(optionBound, new Impl(){});
+    }
+
+    sealed interface Option<T> permits Option.Some, Option.None {
+        record Some<T>(T value) implements Option<T> {}
+        record None<T>() implements Option<T> {}
+
+        static <T, T2 extends T> T unwrapOrElse(Option<T2> option, T defaultValue) {
+            return switch (option) {
+                case Option.Some(T2 value) -> value;
+                case Option.None<T2> _ -> defaultValue;
+            };
+        }
+    }
+
+    interface Bound {}
+    interface Bound2 {}
+    static class Impl implements Bound, Bound2 {}
+    sealed interface Option2<T> permits Option2.Some, Option2.None {
+        record Some<T>(T value) implements Option2<T> {}
+        record None<T>() implements Option2<T> {}
+
+        static <T extends Bound & Bound2> T unwrapOrElse(Option2<T> option, T defaultValue) {
+            return switch (option) {
+                case Option2.Some(T value) -> value;
+                case Option2.None<T> _ -> defaultValue;
+            };
+        }
+    }
+}