diff --git a/build-big-endian.patch b/build-big-endian.patch
index c1972c6..abc6744 100644
--- a/build-big-endian.patch
+++ b/build-big-endian.patch
@@ -1,6 +1,6 @@
-diff -up firefox-55.0/gfx/skia/skia/include/core/SkColorPriv.h.big-endian firefox-55.0/gfx/skia/skia/include/core/SkColorPriv.h
---- firefox-55.0/gfx/skia/skia/include/core/SkColorPriv.h.big-endian	2017-07-31 18:20:55.000000000 +0200
-+++ firefox-55.0/gfx/skia/skia/include/core/SkColorPriv.h	2017-08-03 12:06:32.653090806 +0200
+diff -up firefox-55.0.3/gfx/skia/skia/include/core/SkColorPriv.h.big-endian firefox-55.0.3/gfx/skia/skia/include/core/SkColorPriv.h
+--- firefox-55.0.3/gfx/skia/skia/include/core/SkColorPriv.h.big-endian	2017-07-31 18:20:55.000000000 +0200
++++ firefox-55.0.3/gfx/skia/skia/include/core/SkColorPriv.h	2017-09-01 15:00:06.186520823 +0200
 @@ -31,7 +31,7 @@
   *
   *  Here we enforce this constraint.
@@ -27,9 +27,9 @@ diff -up firefox-55.0/gfx/skia/skia/include/core/SkColorPriv.h.big-endian firefo
  
  #if defined(SK_PMCOLOR_IS_RGBA) && defined(SK_PMCOLOR_IS_BGRA)
      #error "can't define PMCOLOR to be RGBA and BGRA"
-diff -up firefox-55.0/gfx/skia/skia/include/core/SkImageInfo.h.big-endian firefox-55.0/gfx/skia/skia/include/core/SkImageInfo.h
---- firefox-55.0/gfx/skia/skia/include/core/SkImageInfo.h.big-endian	2017-07-31 18:20:55.000000000 +0200
-+++ firefox-55.0/gfx/skia/skia/include/core/SkImageInfo.h	2017-08-03 12:06:32.653090806 +0200
+diff -up firefox-55.0.3/gfx/skia/skia/include/core/SkImageInfo.h.big-endian firefox-55.0.3/gfx/skia/skia/include/core/SkImageInfo.h
+--- firefox-55.0.3/gfx/skia/skia/include/core/SkImageInfo.h.big-endian	2017-07-31 18:20:55.000000000 +0200
++++ firefox-55.0.3/gfx/skia/skia/include/core/SkImageInfo.h	2017-09-01 15:00:06.186520823 +0200
 @@ -83,7 +83,8 @@ enum SkColorType {
  #elif SK_PMCOLOR_BYTE_ORDER(R,G,B,A)
      kN32_SkColorType = kRGBA_8888_SkColorType,
@@ -40,9 +40,9 @@ diff -up firefox-55.0/gfx/skia/skia/include/core/SkImageInfo.h.big-endian firefo
  #endif
  };
  
-diff -up firefox-55.0/gfx/skia/skia/include/gpu/GrColor.h.big-endian firefox-55.0/gfx/skia/skia/include/gpu/GrColor.h
---- firefox-55.0/gfx/skia/skia/include/gpu/GrColor.h.big-endian	2017-07-31 18:20:55.000000000 +0200
-+++ firefox-55.0/gfx/skia/skia/include/gpu/GrColor.h	2017-08-03 12:06:32.653090806 +0200
+diff -up firefox-55.0.3/gfx/skia/skia/include/gpu/GrColor.h.big-endian firefox-55.0.3/gfx/skia/skia/include/gpu/GrColor.h
+--- firefox-55.0.3/gfx/skia/skia/include/gpu/GrColor.h.big-endian	2017-07-31 18:20:55.000000000 +0200
++++ firefox-55.0.3/gfx/skia/skia/include/gpu/GrColor.h	2017-09-01 15:00:06.186520823 +0200
 @@ -74,8 +74,13 @@ static inline GrColor GrColorPackA4(unsi
   *  Since premultiplied means that alpha >= color, we construct a color with
   *  each component==255 and alpha == 0 to be "illegal"
@@ -58,9 +58,9 @@ diff -up firefox-55.0/gfx/skia/skia/include/gpu/GrColor.h.big-endian firefox-55.
  #define GrColor_WHITE 0xFFFFFFFF
  #define GrColor_TRANSPARENT_BLACK 0x0
  
-diff -up firefox-55.0/gfx/skia/skia/include/gpu/GrTypes.h.big-endian firefox-55.0/gfx/skia/skia/include/gpu/GrTypes.h
---- firefox-55.0/gfx/skia/skia/include/gpu/GrTypes.h.big-endian	2017-07-31 18:20:55.000000000 +0200
-+++ firefox-55.0/gfx/skia/skia/include/gpu/GrTypes.h	2017-08-03 12:06:32.653090806 +0200
+diff -up firefox-55.0.3/gfx/skia/skia/include/gpu/GrTypes.h.big-endian firefox-55.0.3/gfx/skia/skia/include/gpu/GrTypes.h
+--- firefox-55.0.3/gfx/skia/skia/include/gpu/GrTypes.h.big-endian	2017-07-31 18:20:55.000000000 +0200
++++ firefox-55.0.3/gfx/skia/skia/include/gpu/GrTypes.h	2017-09-01 15:00:06.187520823 +0200
 @@ -326,15 +326,13 @@ enum GrPixelConfig {
  static const int kGrPixelConfigCnt = kLast_GrPixelConfig + 1;
  
@@ -79,9 +79,9 @@ diff -up firefox-55.0/gfx/skia/skia/include/gpu/GrTypes.h.big-endian firefox-55.
  #endif
  
  // Returns true if the pixel config is a GPU-specific compressed format
-diff -up firefox-55.0/js/src/jit/none/MacroAssembler-none.h.big-endian firefox-55.0/js/src/jit/none/MacroAssembler-none.h
---- firefox-55.0/js/src/jit/none/MacroAssembler-none.h.big-endian	2017-07-31 18:20:48.000000000 +0200
-+++ firefox-55.0/js/src/jit/none/MacroAssembler-none.h	2017-08-04 11:31:18.074582783 +0200
+diff -up firefox-55.0.3/js/src/jit/none/MacroAssembler-none.h.big-endian firefox-55.0.3/js/src/jit/none/MacroAssembler-none.h
+--- firefox-55.0.3/js/src/jit/none/MacroAssembler-none.h.big-endian	2017-07-31 18:20:48.000000000 +0200
++++ firefox-55.0.3/js/src/jit/none/MacroAssembler-none.h	2017-09-01 15:03:38.257602029 +0200
 @@ -48,7 +48,7 @@ static constexpr Register WasmIonExitReg
  
  static constexpr Register WasmIonExitRegReturnData { Registers::invalid_reg };
@@ -91,13 +91,22 @@ diff -up firefox-55.0/js/src/jit/none/MacroAssembler-none.h.big-endian firefox-5
  static constexpr Register WasmIonExitRegD0 { Registers::invalid_reg };
  static constexpr Register WasmIonExitRegD1 { Registers::invalid_reg };
  static constexpr Register WasmIonExitRegD2 { Registers::invalid_reg };
-@@ -197,8 +197,8 @@ class MacroAssemblerNone : public Assemb
+@@ -153,6 +153,8 @@ class Assembler : public AssemblerShared
+ 
+     static uintptr_t GetPointer(uint8_t*) { MOZ_CRASH(); }
+ 
++    static bool HasRoundInstruction(RoundingMode) { return false; }
++
+     void verifyHeapAccessDisassembly(uint32_t begin, uint32_t end,
+                                      const Disassembler::HeapAccess& heapAccess)
+     {
+@@ -196,9 +198,7 @@ class MacroAssemblerNone : public Assemb
+     static bool SupportsSimd() { return false; }
      static bool SupportsUnalignedAccesses() { return false; }
  
-     static bool HasRoundInstruction(RoundingMode) { return false; }
+-    static bool HasRoundInstruction(RoundingMode) { return false; }
 -
 -    void executableCopy(void*, bool) { MOZ_CRASH(); }
-+    
 +    void executableCopy(void*, bool flushICache = true) { MOZ_CRASH(); }
      void copyJumpRelocationTable(uint8_t*) { MOZ_CRASH(); }
      void copyDataRelocationTable(uint8_t*) { MOZ_CRASH(); }
diff --git a/firefox.spec b/firefox.spec
index db73936..9f5fb8d 100644
--- a/firefox.spec
+++ b/firefox.spec
@@ -129,6 +129,7 @@ Patch25:        rhbz-1219542-s390-build.patch
 Patch26:        build-icu-big-endian.patch
 Patch27:        mozilla-1335250.patch
 Patch28:        build-1360521-missing-cheddar.patch
+# Also fixes s390x: https://bugzilla.mozilla.org/show_bug.cgi?id=1376268
 Patch29:        build-big-endian.patch
 Patch30:        fedora-build.patch
 Patch31:        build-ppc64-s390x-curl.patch