diff --git a/compiler-rt/lib/asan/asan_fuchsia.cpp b/compiler-rt/lib/asan/asan_fuchsia.cpp
--- a/compiler-rt/lib/asan/asan_fuchsia.cpp
+++ b/compiler-rt/lib/asan/asan_fuchsia.cpp
@@ -196,6 +196,10 @@
   return false;
 }
 
+void FlushUnneededASanShadowMemory(uptr p, uptr size) {
+  __sanitizer_fill_shadow(p, size, 0, 0);
+}
+
 }  // namespace __asan
 
 // These are declared (in extern "C") by <zircon/sanitizer.h>.
diff --git a/compiler-rt/lib/asan/asan_poisoning.cpp b/compiler-rt/lib/asan/asan_poisoning.cpp
--- a/compiler-rt/lib/asan/asan_poisoning.cpp
+++ b/compiler-rt/lib/asan/asan_poisoning.cpp
@@ -62,17 +62,13 @@
   }
 };
 
+#if !SANITIZER_FUCHSIA
 void FlushUnneededASanShadowMemory(uptr p, uptr size) {
   // Since asan's mapping is compacting, the shadow chunk may be
   // not page-aligned, so we only flush the page-aligned portion.
   ReleaseMemoryPagesToOS(MemToShadow(p), MemToShadow(p + size));
-
-#if SANITIZER_FUCHSIA
-  // In Fuchsia ReleaseMemoryPagesToOS is a no-op. __sanitizer_fill_shadow
-  // With a 0 value and a 0 threshold will decommit the shadow pages.
-  __sanitizer_fill_shadow(p, size, 0, 0);
-#endif
 }
+#endif  // !SANITIZER_FUCHSIA
 
 void AsanPoisonOrUnpoisonIntraObjectRedzone(uptr ptr, uptr size, bool poison) {
   uptr end = ptr + size;