diff --git a/.circleci/config.yml b/.circleci/config.yml
index 9d4f6b99e102e..68573dd5878e7 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -705,6 +705,7 @@ jobs:
             lto0.test_exceptions_allowed_uncaught
             lto0.test_longjmp_standalone_standalone
             lto0.test_embind_i64_val
+            thinlto0.test_pthread_dlsym
             core3
             core2g.test_externref
             corez.test_dylink_iostream
diff --git a/test/codesize/test_codesize_cxx_lto.json b/test/codesize/test_codesize_cxx_lto.json
index 2ebca12e429b1..308be06dbfe4a 100644
--- a/test/codesize/test_codesize_cxx_lto.json
+++ b/test/codesize/test_codesize_cxx_lto.json
@@ -1,10 +1,10 @@
 {
   "a.out.js": 18562,
   "a.out.js.gz": 7668,
-  "a.out.nodebug.wasm": 101956,
-  "a.out.nodebug.wasm.gz": 39461,
-  "total": 120518,
-  "total_gz": 47129,
+  "a.out.nodebug.wasm": 101954,
+  "a.out.nodebug.wasm.gz": 39462,
+  "total": 120516,
+  "total_gz": 47130,
   "sent": [
     "a (emscripten_resize_heap)",
     "b (_setitimer_js)",
diff --git a/tools/system_libs.py b/tools/system_libs.py
index 5073e0614f3f5..b443f6dc86c9c 100644
--- a/tools/system_libs.py
+++ b/tools/system_libs.py
@@ -1080,6 +1080,8 @@ class libc(MuslInternalLibrary,
 
   def __init__(self, **kwargs):
     self.non_lto_files = self.get_libcall_files()
+    # TODO(https://github.com/emscripten-core/emscripten/issues/26506)
+    self.non_lto_files.append(utils.path_from_root('system/lib/libc/musl/src/locale/uselocale.c'))
     super().__init__(**kwargs)
 
   def get_libcall_files(self):