diff --git a/linker/dlfcn.cpp b/linker/dlfcn.cpp
index 255363f..ec6850a 100644
--- a/linker/dlfcn.cpp
+++ b/linker/dlfcn.cpp
@@ -284,6 +284,7 @@
 }
 
 void __loader_cfi_fail(uint64_t CallSiteTypeId, void* Ptr, void *DiagData, void *CallerPc) {
+  ScopedPthreadMutexLocker locker(&g_dl_mutex);
   CFIShadowWriter::CfiFail(CallSiteTypeId, Ptr, DiagData, CallerPc);
 }