diff -r 95c2853dd616 -r 68902f8a1ef0 src/Pure/Admin/build_polyml.scala
--- a/src/Pure/Admin/build_polyml.scala	Wed Sep 30 23:37:07 2020 +0200
+++ b/src/Pure/Admin/build_polyml.scala	Thu Oct 01 15:56:34 2020 +0200
@@ -64,8 +64,8 @@
     val platform_64 = "x86_64-" + platform_os
 
     val info =
-      platform_info.get(platform_os) getOrElse
-        error("Bad OS platform: " + quote(platform_os))
+      platform_info.getOrElse(platform_os,
+        error("Bad OS platform: " + quote(platform_os)))
 
     val settings =
       msys_root match {