diff --git a/src/base/allocator/partition_allocator/src/partition_alloc/partition_alloc_base/threading/platform_thread_posix.cc b/src/base/allocator/partition_allocator/src/partition_alloc/partition_alloc_base/threading/platform_thread_posix.cc
index 47e4368908..557b6b55e7 100644
--- a/src/base/allocator/partition_allocator/src/partition_alloc/partition_alloc_base/threading/platform_thread_posix.cc
+++ b/src/base/allocator/partition_allocator/src/partition_alloc/partition_alloc_base/threading/platform_thread_posix.cc
@@ -59,7 +59,9 @@ thread_local bool g_is_main_thread = true;
 class InitAtFork {
  public:
   InitAtFork() {
+#if !defined(__MUSL__)
     pthread_atfork(nullptr, nullptr, internal::InvalidateTidCache);
+#endif
   }
 };
 
diff --git a/src/base/allocator/partition_allocator/src/partition_alloc/partition_root.cc b/src/base/allocator/partition_allocator/src/partition_alloc/partition_root.cc
index 96f0cb6a8f..18a5dd518b 100644
--- a/src/base/allocator/partition_allocator/src/partition_alloc/partition_root.cc
+++ b/src/base/allocator/partition_allocator/src/partition_alloc/partition_root.cc
@@ -297,7 +297,11 @@ void PartitionAllocMallocInitOnce() {
     return;
   }
 
-#if PA_BUILDFLAG(IS_LINUX) || PA_BUILDFLAG(IS_CHROMEOS)
+#if defined(__MUSL__)
+  static_cast<void>(BeforeForkInParent);
+  static_cast<void>(AfterForkInParent);
+  static_cast<void>(AfterForkInChild);
+#elif PA_BUILDFLAG(IS_LINUX) || PA_BUILDFLAG(IS_CHROMEOS)
   // When fork() is called, only the current thread continues to execute in the
   // child process. If the lock is held, but *not* by this thread when fork() is
   // called, we have a deadlock.