diff --git a/postfix/makedefs b/postfix/makedefs
index 285224b0c..47761f1c1 100644
--- a/postfix/makedefs
+++ b/postfix/makedefs
@@ -224,12 +224,12 @@ case $# in
      dcosx*) SYSTEM=$VERSION;;
     esac;;
  # Unsupported debug-only mode. Not suitable for cross-platform tests.
-2|3) SYSTEM="$1"; RELEASE="$2"; VERSION="$3";;
- *) echo usage: $0 [system release version] 1>&2; exit 1;;
+ 2) SYSTEM="$1"; RELEASE="$2";;
+ *) echo usage: $0 [system release] 1>&2; exit 1;;
 esac
 
-case "$SYSTEM.$VERSION" in
- Linux.#*-Alpine*)
+case "`PATH=/bin:/usr/bin ldd /bin/sh`" in
+ *-musl-*)
     case "$CCARGS" in
      *-DNO_DNSSEC*) ;;
      *) echo Warning: libc-musl breaks DANE/TLSA security. 1>&2
diff --git a/postfix/src/global/mail_version.h b/postfix/src/global/mail_version.h
index 0d66e63d5..77b7c554d 100644
--- a/postfix/src/global/mail_version.h
+++ b/postfix/src/global/mail_version.h
@@ -20,7 +20,7 @@
   * Patches change both the patchlevel and the release date. Snapshots have no
   * patchlevel; they change the release date only.
   */
-#define MAIL_RELEASE_DATE	"20200503"
+#define MAIL_RELEASE_DATE	"20200504"
 #define MAIL_VERSION_NUMBER	"3.6"
 
 #ifdef SNAPSHOT