diff --git a/NEWS b/NEWS
index 952d122fb91..36da15cf32b 100644
--- a/NEWS
+++ b/NEWS
@@ -14,6 +14,7 @@ PHP                                                                        NEWS
     array). (ilutov)
   . Fixed bug GH-19480 (error_log php.ini cannot be unset when open_basedir is
     configured). (nielsdos)
+  . Fixed bug GH-20002 (Broken build on *BSD with MSAN). (outtersg)
 
 - Curl:
   . Fix cloning of CURLOPT_POSTFIELDS when using the clone operator instead
diff --git a/Zend/zend_string.c b/Zend/zend_string.c
index dfe059359aa..e9ebee08f43 100644
--- a/Zend/zend_string.c
+++ b/Zend/zend_string.c
@@ -505,8 +505,10 @@ ZEND_API zend_string *zend_string_concat3(
 	return res;
 }
 
-/* strlcpy and strlcat are not intercepted by msan, so we need to do it ourselves. */
-#if __has_feature(memory_sanitizer)
+/* strlcpy and strlcat are not always intercepted by msan, so we need to do it
+ * ourselves. Apply a simple heuristic to determine the platforms that need it.
+ * See https://github.com/php/php-src/issues/20002. */
+#if __has_feature(memory_sanitizer) && !defined(__FreeBSD__) && !defined(__NetBSD__) && !defined(__APPLE__)
 static size_t (*libc_strlcpy)(char *__restrict, const char *__restrict, size_t);
 size_t strlcpy(char *__restrict dest, const char *__restrict src, size_t n)
 {