diff --git a/srcpkgs/granite/patches/fix-build-with-vala-0-42.patch b/srcpkgs/granite/patches/fix-build-with-vala-0-42.patch
new file mode 100644
index 00000000000..037d1f270c3
--- /dev/null
+++ b/srcpkgs/granite/patches/fix-build-with-vala-0-42.patch
@@ -0,0 +1,40 @@
+--- lib/Widgets/SeekBar.vala
++++ lib/Widgets/SeekBar.vala
+@@ -26,7 +26,7 @@
+ 
+ public class Granite.SeekBar : Gtk.Grid {
+     private double _playback_duration;
+-    private double _playback_progress;
++    private double _playback_progress = 0.0;
+ 
+     /*
+      * The time of the full duration of the playback.
+@@ -68,7 +68,6 @@ public class Granite.SeekBar : Gtk.Grid {
+             scale.set_value (progress);
+             progression_label.label = DateTime.seconds_to_time ((int) (progress * playback_duration));
+         }
+-        default = 0.0;
+     }
+ 
+     /*
+--- lib/Widgets/StorageBar.vala
++++ lib/Widgets/StorageBar.vala
+@@ -83,7 +83,7 @@ public class Granite.Widgets.StorageBar : Gtk.Box {
+         }
+     }
+ 
+-    private uint64 _total_usage;
++    private uint64 _total_usage = 0;
+ 
+     public uint64 total_usage {
+         get {
+@@ -94,8 +94,6 @@ public class Granite.Widgets.StorageBar : Gtk.Box {
+             _total_usage = uint64.min (value, storage);
+             update_size_description ();
+         }
+-
+-        default = 0;
+     }
+ 
+     public int inner_margin_sides {
+