diff --git a/pkgs/desktops/gnome-3/core/gnome-settings-daemon/default.nix b/pkgs/desktops/gnome-3/core/gnome-settings-daemon/default.nix
index 6929f821e379..b9f33ce73a8a 100644
--- a/pkgs/desktops/gnome-3/core/gnome-settings-daemon/default.nix
+++ b/pkgs/desktops/gnome-3/core/gnome-settings-daemon/default.nix
@@ -95,6 +95,12 @@ stdenv.mkDerivation rec {
     "-Dudev_dir=${placeholder "out"}/lib/udev"
   ];
 
+  NIX_CFLAGS_COMPILE = [
+    # Default for release buildtype but passed manually because
+    # we're using plain
+    "-DG_DISABLE_CAST_CHECKS"
+  ];
+
   # So the polkit policy can reference /run/current-system/sw/bin/gnome-settings-daemon/gsd-backlight-helper
   postFixup = ''
     mkdir -p $out/bin/gnome-settings-daemon
diff --git a/pkgs/desktops/pantheon/services/elementary-settings-daemon/default.nix b/pkgs/desktops/pantheon/services/elementary-settings-daemon/default.nix
index d8514c51f4f7..b4391b2e1b05 100644
--- a/pkgs/desktops/pantheon/services/elementary-settings-daemon/default.nix
+++ b/pkgs/desktops/pantheon/services/elementary-settings-daemon/default.nix
@@ -150,6 +150,12 @@ stdenv.mkDerivation rec {
     "-Dudev_dir=${placeholder "out"}/lib/udev"
   ];
 
+  NIX_CFLAGS_COMPILE = [
+    # Default for release buildtype but passed manually because
+    # we're using plain
+    "-DG_DISABLE_CAST_CHECKS"
+  ];
+
   passthru = {
     updateScript = gnome3.updateScript {
       packageName = projectName;
diff --git a/pkgs/development/libraries/glib/default.nix b/pkgs/development/libraries/glib/default.nix
index ecbcbea13941..7b226f9fc80b 100644
--- a/pkgs/development/libraries/glib/default.nix
+++ b/pkgs/development/libraries/glib/default.nix
@@ -98,8 +98,12 @@ stdenv.mkDerivation rec {
 
   LC_ALL = "en_US.UTF-8";
 
-  NIX_CFLAGS_COMPILE = (optional stdenv.isSunOS "-DBSD_COMP")
-    ++ [ "-Wno-error=nonnull" ];
+  NIX_CFLAGS_COMPILE = [
+    "-Wno-error=nonnull"
+    # Default for release buildtype but passed manually because
+    # we're using plain
+    "-DG_DISABLE_CAST_CHECKS"
+  ];
 
   postPatch = ''
     # substitute fix-gio-launch-desktop-path.patch
diff --git a/pkgs/development/libraries/gtk+/3.x.nix b/pkgs/development/libraries/gtk+/3.x.nix
index 94b745794f1e..40be17fcac7c 100644
--- a/pkgs/development/libraries/gtk+/3.x.nix
+++ b/pkgs/development/libraries/gtk+/3.x.nix
@@ -77,6 +77,13 @@ stdenv.mkDerivation rec {
     "-Dtests=false"
   ];
 
+  # These are the defines that'd you'd get with --enable-debug=minimum (default).
+  # See: https://developer.gnome.org/gtk3/stable/gtk-building.html#extra-configuration-options
+  NIX_CFLAGS_COMPILE = [
+    "-DG_ENABLE_DEBUG"
+    "-DG_DISABLE_CAST_CHECKS"
+  ];
+
   postPatch = ''
     files=(
       build-aux/meson/post-install.py