diff --git a/testing/firefox/checksums b/testing/firefox/checksums
index f5866f32..e01aa9f3 100644
--- a/testing/firefox/checksums
+++ b/testing/firefox/checksums
@@ -1,4 +1,5 @@
-d6b9e4472f73c5a1726f4b33d1749aff7831b73915ab6797b66b5d23c5604cb0a5
+726b06d8cc5764564766c8416283cc0b14fe188339a24aa288cebe4703589b7622
+bd231369e10f0300360b79ae2e9b429f1d5833f6a46b615722979c38b6ebb70882
 ee279241e461011e2265086328d9d0a913ab938bb81aa97fa22b8b9b7edf5e33bc
 8c0f419eb138061e67dbe2ac73e9c8332649fb90aacb57ac4f00d5de94c0cf23a8
 3bfec8b5e7cb94481d94e1039a602e14564c8a6da5a28f089ce4a69d23f9e42bbb
diff --git a/testing/firefox/patches/fix-overalignment.patch b/testing/firefox/patches/fix-overalignment.patch
new file mode 100644
index 00000000..20c2d796
--- /dev/null
+++ b/testing/firefox/patches/fix-overalignment.patch
@@ -0,0 +1,50 @@
+diff --git a/js/public/Utility.h b/js/public/Utility.h
+index 5a3002b..8927d65 100644
+--- a/js/public/Utility.h
++++ b/js/public/Utility.h
+@@ -478,6 +478,9 @@ static inline void js_free(void* p) {
+ #define JS_DECLARE_NEW_METHODS(NEWNAME, ALLOCATOR, QUALIFIERS)              \
+   template <class T, typename... Args>                                      \
+   QUALIFIERS T* MOZ_HEAP_ALLOCATOR NEWNAME(Args&&... args) {                \
++    static_assert(                                                          \
++        alignof(T) <= alignof(max_align_t),                                 \
++        "over-aligned type is not supported by JS_DECLARE_NEW_METHODS");    \
+     void* memory = ALLOCATOR(sizeof(T));                                    \
+     return MOZ_LIKELY(memory) ? new (memory) T(std::forward<Args>(args)...) \
+                               : nullptr;                                    \
+@@ -494,6 +497,9 @@ static inline void js_free(void* p) {
+ #define JS_DECLARE_NEW_ARENA_METHODS(NEWNAME, ALLOCATOR, QUALIFIERS)           \
+   template <class T, typename... Args>                                         \
+   QUALIFIERS T* MOZ_HEAP_ALLOCATOR NEWNAME(arena_id_t arena, Args&&... args) { \
++    static_assert(                                                             \
++        alignof(T) <= alignof(max_align_t),                                    \
++        "over-aligned type is not supported by JS_DECLARE_NEW_ARENA_METHODS"); \
+     void* memory = ALLOCATOR(arena, sizeof(T));                                \
+     return MOZ_LIKELY(memory) ? new (memory) T(std::forward<Args>(args)...)    \
+                               : nullptr;                                       \
+diff --git a/js/src/gc/GCMarker.h b/js/src/gc/GCMarker.h
+index 495e66c..053ba90 100644
+--- a/js/src/gc/GCMarker.h
++++ b/js/src/gc/GCMarker.h
+@@ -274,7 +274,7 @@ enum ShouldReportMarkTime : bool {
+ 
+ } /* namespace gc */
+ 
+-class alignas(TypicalCacheLineSize) GCMarker {
++class GCMarker {
+   enum MarkingState : uint8_t {
+     // Have not yet started marking.
+     NotActive,
+diff --git a/js/src/gc/Nursery.h b/js/src/gc/Nursery.h
+index ae1e8c2..3dde209 100644
+--- a/js/src/gc/Nursery.h
++++ b/js/src/gc/Nursery.h
+@@ -67,7 +67,7 @@ class GCSchedulingTunables;
+ class TenuringTracer;
+ }  // namespace gc
+ 
+-class alignas(TypicalCacheLineSize) Nursery {
++class Nursery {
+  public:
+   explicit Nursery(gc::GCRuntime* gc);
+   ~Nursery();
diff --git a/testing/firefox/sources b/testing/firefox/sources
index d74f9422..a6742f3c 100644
--- a/testing/firefox/sources
+++ b/testing/firefox/sources
@@ -1,4 +1,5 @@
-https://ftp.mozilla.org/pub/firefox/releases/116.0b2/source/firefox-116.0b2.source.tar.xz
+https://ftp.mozilla.org/pub/firefox/releases/116.0b8/source/firefox-116.0b8.source.tar.xz
+patches/fix-overalignment.patch
 patches/musl-sandbox.patch
 patches/no-atk.patch
 patches/no-dbus.patch
diff --git a/testing/firefox/version b/testing/firefox/version
index 4cf28434..f455d3ea 100644
--- a/testing/firefox/version
+++ b/testing/firefox/version
@@ -1 +1 @@
-116.0b2 1
+116.0b8 1