diff --git a/compiler-rt/test/msan/allocator_mapping.cc b/compiler-rt/test/msan/allocator_mapping.cc
index 954b8dfef3be..f47d9a63e09f 100644
--- a/compiler-rt/test/msan/allocator_mapping.cc
+++ b/compiler-rt/test/msan/allocator_mapping.cc
@@ -4,6 +4,11 @@
 //
 // RUN: %clangxx_msan -O0 %s -o %t_1
 // RUN: %clangxx_msan -O0 -DHEAP_ADDRESS=$(%run %t_1) %s -o %t_2 && %run %t_2
+//
+// This test only makes sense for the 64-bit allocator. The 32-bit allocator
+// does not have a fixed mapping. Exclude platforms that use the 32-bit
+// allocator.
+// UNSUPPORTED: mips64,aarch64
 
 #include <assert.h>
 #include <stdio.h>