diff --git a/lib/common/compiler.h b/lib/common/compiler.h
index e423f2467..4ad55e601 100644
--- a/lib/common/compiler.h
+++ b/lib/common/compiler.h
@@ -281,6 +281,17 @@
 *  Sanitizer
 *****************************************************************/
 
+/* Issue #3240 reports an ASAN failure on an llvm-mingw build. Out of an
+ * abundance of caution, disable our custom poisoning on mingw. */
+#ifdef __MINGW32__
+#ifndef ZSTD_ASAN_DONT_POISON_WORKSPACE
+#define ZSTD_ASAN_DONT_POISON_WORKSPACE 1
+#endif
+#ifndef ZSTD_MSAN_DONT_POISON_WORKSPACE
+#define ZSTD_MSAN_DONT_POISON_WORKSPACE 1
+#endif
+#endif
+
 #if ZSTD_MEMORY_SANITIZER
 /* Not all platforms that support msan provide sanitizers/msan_interface.h.
  * We therefore declare the functions we need ourselves, rather than trying to