diff --git a/app/src/main/java/com/droiddeck/launcher/runtime/BwrapSpawner.kt b/app/src/main/java/com/droiddeck/launcher/runtime/BwrapSpawner.kt
index 6e20ff89d..3d7000228 100644
--- a/app/src/main/java/com/droiddeck/launcher/runtime/BwrapSpawner.kt
+++ b/app/src/main/java/com/droiddeck/launcher/runtime/BwrapSpawner.kt
@@ -300,7 +300,10 @@ object BwrapSpawner {
         // session has Xwayland) it stays on X11, which works. GTK and Qt go by their own settings.
         if (env.containsKey("DISPLAY")) env["XDG_SESSION_TYPE"] = "x11"
         for (name in listOf("MOZ_DISABLE_CONTENT_SANDBOX", "MOZ_DISABLE_GMP_SANDBOX", "MOZ_DISABLE_RDD_SANDBOX",
-                            "MOZ_DISABLE_SOCKET_PROCESS_SANDBOX", "MOZ_DISABLE_UTILITY_SANDBOX")) {
+                            "MOZ_DISABLE_SOCKET_PROCESS_SANDBOX", "MOZ_DISABLE_UTILITY_SANDBOX",
+                            // Android 16 refuses the size seal Firefox puts on a tab's shared
+                            // memory, and the tab then dies on every page (droiddeck-desktop).
+                            "MOZ_SHM_NO_SEALS")) {
             env.putIfAbsent(name, "1")
         }
     }
diff --git a/tools/linuxfs/desktop/droiddeck-desktop b/tools/linuxfs/desktop/droiddeck-desktop
index 7c7883b6a..b69c2a993 100644
--- a/tools/linuxfs/desktop/droiddeck-desktop
+++ b/tools/linuxfs/desktop/droiddeck-desktop
@@ -16,6 +16,11 @@ export QT_QPA_PLATFORMTHEME=lxqt
 # The prefs for this are only advisory and a profile can override them; the environment is not.
 export MOZ_DISABLE_CONTENT_SANDBOX=1 MOZ_DISABLE_GMP_SANDBOX=1 MOZ_DISABLE_RDD_SANDBOX=1
 export MOZ_DISABLE_SOCKET_PROCESS_SANDBOX=1 MOZ_DISABLE_UTILITY_SANDBOX=1
+# Firefox seals the size of the shared memory it hands a tab; on Android 16 (Galaxy S25/S26,
+# RedMagic) adding the seal fails, Firefox only warns, and the tab refuses the unsealed memory
+# ("Shared memory PlatformHandle is not safe to map") and dies on signal 11 - every page. Firefox's
+# own switch skips the seals.
+export MOZ_SHM_NO_SEALS=1
 # pixman composites in software and gives programs shm buffers only, so a Vulkan program on it
 # fails at its swapchain. vulkan (or gles2) composite on the GPU and give programs DMA-BUFs, but
 # stock wlroots allocates through gbm on a real DRM node and the KGSL stand-in is not one ("unable
diff --git a/tools/linuxfs/overlay/usr/local/bin/droiddeck-appimage-run b/tools/linuxfs/overlay/usr/local/bin/droiddeck-appimage-run
index 946a64601..847c272b6 100755
--- a/tools/linuxfs/overlay/usr/local/bin/droiddeck-appimage-run
+++ b/tools/linuxfs/overlay/usr/local/bin/droiddeck-appimage-run
@@ -24,6 +24,8 @@ fi
 # X11, which it picks from the session type.
 export MOZ_DISABLE_CONTENT_SANDBOX=1 MOZ_DISABLE_GMP_SANDBOX=1 MOZ_DISABLE_RDD_SANDBOX=1
 export MOZ_DISABLE_SOCKET_PROCESS_SANDBOX=1 MOZ_DISABLE_UTILITY_SANDBOX=1
+# Android 16 refuses Firefox the size seal on a tab's shared memory; see droiddeck-desktop.
+export MOZ_SHM_NO_SEALS=1
 # sharun images start the app through their own ld.so, patched not to read /etc/ld.so.preload, and
 # drop LD_PRELOAD unless allowed: without this the app never gets the session's pads.
 if [ -s /etc/ld.so.preload ]; then