diff --git a/compiler-rt/lib/gwp_asan/platform_specific/guarded_pool_allocator_posix.cpp b/compiler-rt/lib/gwp_asan/platform_specific/guarded_pool_allocator_posix.cpp
--- a/compiler-rt/lib/gwp_asan/platform_specific/guarded_pool_allocator_posix.cpp
+++ b/compiler-rt/lib/gwp_asan/platform_specific/guarded_pool_allocator_posix.cpp
@@ -97,7 +97,11 @@
   return sysconf(_SC_PAGESIZE);
 }
 
+static bool AtForkHandlersInstalled = false;
 void GuardedPoolAllocator::installAtFork() {
+  Check(!AtForkHandlersInstalled,
+        "atfork() handlers can only be installed once.");
+  AtForkHandlersInstalled = true;
   auto Disable = []() {
     if (auto *S = getSingleton())
       S->disable();
diff --git a/compiler-rt/lib/gwp_asan/tests/late_init.cpp b/compiler-rt/lib/gwp_asan/tests/late_init.cpp
--- a/compiler-rt/lib/gwp_asan/tests/late_init.cpp
+++ b/compiler-rt/lib/gwp_asan/tests/late_init.cpp
@@ -19,6 +19,7 @@
   gwp_asan::options::Options Opts;
   Opts.Enabled = true;
   Opts.SampleRate = 1;
+  Opts.InstallForkHandlers = false;
 
   GPA.init(Opts);
   EXPECT_TRUE(GPA.shouldSample());