diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 3e84e25f360fa..b4f3846e81339 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -931,6 +931,7 @@ Bug Fixes to C++ Support
 - Improved handling of variables with ``consteval`` constructors, to
   consistently treat the initializer as manifestly constant-evaluated.
   (#GH135281)
+- Fix a crash in the presence of invalid base classes. (#GH147186)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index eae8281964692..59e6e0af4b5b0 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -2252,7 +2252,7 @@ void Parser::ParseBaseClause(Decl *ClassDecl) {
   while (true) {
     // Parse a base-specifier.
     BaseResult Result = ParseBaseSpecifier(ClassDecl);
-    if (Result.isInvalid()) {
+    if (!Result.isUsable()) {
       // Skip the rest of this base specifier, up until the comma or
       // opening brace.
       SkipUntil(tok::comma, tok::l_brace, StopAtSemi | StopBeforeMatch);
diff --git a/clang/test/SemaCXX/invalid-base-inheritance.cpp b/clang/test/SemaCXX/invalid-base-inheritance.cpp
new file mode 100644
index 0000000000000..b9615a5666970
--- /dev/null
+++ b/clang/test/SemaCXX/invalid-base-inheritance.cpp
@@ -0,0 +1,16 @@
+// Tests that invalid base-specifiers no longer crash the compiler.
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %s
+
+namespace GH147186 {
+
+class X; // expected-note {{forward declaration of 'GH147186::X'}} expected-note {{forward declaration of 'GH147186::X'}}
+
+class A : X { // expected-error {{base class has incomplete type}}
+};
+
+class Y : int { // expected-error {{expected class name}}
+};
+
+class Z : X*, virtual int { // expected-error {{base class has incomplete type}} expected-error {{expected class name}}
+};
+}