--- a/build/depends.py	2019-11-27 01:02:42.000000000 +0100
+++ b/build/depends.py	2020-01-05 22:22:49.241325116 +0100
@@ -1304,7 +1304,11 @@
             'preferences/dialog/dlgprefvinyldlg.ui',
             'preferences/dialog/dlgprefwaveformdlg.ui',
         ]
-        map(Qt.uic(build), ui_files)
+
+        # In Python 3.x, map() returns a "map object" (instead of a list),
+        # which is evaluated on-demand rather than at once. To invoke uic
+        # for all *.ui files at once, we need to cast it to a list here.
+        list(map(Qt.uic(build), ui_files))
 
         if build.platform_is_windows:
             # Add Windows resource file with icons and such