diff --git a/Meta/Lagom/CMakeLists.txt b/Meta/Lagom/CMakeLists.txt
index 36e8781fd4..d555a7e391 100644
--- a/Meta/Lagom/CMakeLists.txt
+++ b/Meta/Lagom/CMakeLists.txt
@@ -497,6 +497,22 @@ if (BUILD_LAGOM)
         add_executable(test262-runner ../../Tests/LibJS/test262-runner.cpp)
         target_link_libraries(test262-runner LibJS LibCore)
 
+        if (CMAKE_SYSTEM_NAME STREQUAL "Linux")
+            include(CheckCSourceCompiles)
+            # Check for musl's declaration of __assert_fail
+            check_c_source_compiles(
+                "
+                #include <assert.h>
+                __attribute__((__noreturn__)) void __assert_fail(char const* assertion, char const* file, int line, char const* function) {}
+                int main() {}
+                "
+                ASSERT_FAIL_HAS_INT
+            )
+        endif()
+        if (ASSERT_FAIL_HAS_INT OR EMSCRIPTEN)
+            target_compile_definitions(test262-runner PRIVATE ASSERT_FAIL_HAS_INT)
+        endif()
+
         add_executable(wasm ../../Userland/Utilities/wasm.cpp)
         target_link_libraries(wasm LibCore LibWasm LibLine LibMain)
 
diff --git a/Tests/LibJS/test262-runner.cpp b/Tests/LibJS/test262-runner.cpp
index 84bc611ced..81d3a87c15 100644
--- a/Tests/LibJS/test262-runner.cpp
+++ b/Tests/LibJS/test262-runner.cpp
@@ -556,13 +556,16 @@ static bool g_in_assert = false;
     exit(12);
 }
 
+// FIXME: Use a SIGABRT handler here instead of overriding internal libc assertion handlers.
+//        Fixing this will likely require updating the test driver as well to pull the assertion failure
+//        message out of stderr rather than from the json object printed to stdout.
 #ifdef AK_OS_SERENITY
 void __assertion_failed(char const* assertion)
 {
     handle_failed_assert(assertion);
 }
 #else
-#    ifdef AK_OS_EMSCRIPTEN
+#    ifdef ASSERT_FAIL_HAS_INT /* Set by CMake */
 extern "C" __attribute__((__noreturn__)) void __assert_fail(char const* assertion, char const* file, int line, char const* function)
 #    else
 extern "C" __attribute__((__noreturn__)) void __assert_fail(char const* assertion, char const* file, unsigned int line, char const* function)