diff --git a/lib/base/sanitizers.h b/lib/base/sanitizers.h
index 2c965c48..37ff3117 100644
--- a/lib/base/sanitizers.h
+++ b/lib/base/sanitizers.h
@@ -19,11 +19,12 @@
 namespace jxl {
 namespace msan {
 
+#if JXL_MEMORY_SANITIZER
+
 // Chosen so that kSanitizerSentinel is four copies of kSanitizerSentinelByte.
 constexpr uint8_t kSanitizerSentinelByte = 0x48;
 constexpr float kSanitizerSentinel = 205089.125f;
 
-#if JXL_MEMORY_SANITIZER
 
 static JXL_INLINE JXL_MAYBE_UNUSED void PoisonMemory(const volatile void* m,
                                                      size_t size) {