diff --git a/js/src/jit/mips-shared/Architecture-mips-shared.cpp b/js/src/jit/mips-shared/Architecture-mips-shared.cpp
index 37c3a4c7fbf2..11815903a341 100644
--- a/js/src/jit/mips-shared/Architecture-mips-shared.cpp
+++ b/js/src/jit/mips-shared/Architecture-mips-shared.cpp
@@ -23,7 +23,7 @@ uint32_t GetMIPSFlags()
     static uint32_t flags = 0;
     if (isSet)
         return flags;
-#ifdef JS_SIMULATOR_MIPS32
+#if defined(JS_SIMULATOR_MIPS32) || defined(JS_SIMULATOR_MIPS64)
     isSet = true;
     flags |= HWCAP_FPU;
     return flags;
@@ -46,7 +46,7 @@ uint32_t GetMIPSFlags()
 #endif
 
     return flags;
-#endif // JS_SIMULATOR_MIPS32
+#endif // JS_SIMULATOR_MIPS32 || JS_SIMULATOR_MIPS64
 }
 
 bool hasFPU()
diff --git a/js/src/jit/mips-shared/Architecture-mips-shared.h b/js/src/jit/mips-shared/Architecture-mips-shared.h
index c0048e4d2086..8cea20f8be25 100644
--- a/js/src/jit/mips-shared/Architecture-mips-shared.h
+++ b/js/src/jit/mips-shared/Architecture-mips-shared.h
@@ -17,11 +17,13 @@
 // gcc appears to use _mips_hard_float to denote
 // that the target is a hard-float target.
 #ifdef _mips_hard_float
-#define JS_CODEGEN_MIPS32_HARDFP
+#define JS_CODEGEN_MIPS_HARDFP
 #endif
 
-#if _MIPS_SIM == _ABIO32
+#if (defined(_MIPS_SIM) && (_MIPS_SIM == _ABIO32)) || defined(JS_SIMULATOR_MIPS32)
 #define USES_O32_ABI
+#elif (defined(_MIPS_SIM) && (_MIPS_SIM == _ABI64)) || defined(JS_SIMULATOR_MIPS64)
+#define USES_N64_ABI
 #else
 #error "Unsupported ABI"
 #endif
@@ -73,6 +75,7 @@ class Registers
         a1 = r5,
         a2 = r6,
         a3 = r7,
+#if defined(USES_O32_ABI)
         t0 = r8,
         t1 = r9,
         t2 = r10,
@@ -81,6 +84,24 @@ class Registers
         t5 = r13,
         t6 = r14,
         t7 = r15,
+        ta0 = t4,
+        ta1 = t5,
+        ta2 = t6,
+        ta3 = t7,
+#elif defined(USES_N64_ABI)
+        a4 = r8,
+        a5 = r9,
+        a6 = r10,
+        a7 = r11,
+        t0 = r12,
+        t1 = r13,
+        t2 = r14,
+        t3 = r15,
+        ta0 = a4,
+        ta1 = a5,
+        ta2 = a6,
+        ta3 = a7,
+#endif
         s0 = r16,
         s1 = r17,
         s2 = r18,
@@ -140,10 +161,10 @@ class Registers
         (1 << Registers::t1) |
         (1 << Registers::t2) |
         (1 << Registers::t3) |
-        (1 << Registers::t4) |
-        (1 << Registers::t5) |
-        (1 << Registers::t6) |
-        (1 << Registers::t7);
+        (1 << Registers::ta0) |
+        (1 << Registers::ta1) |
+        (1 << Registers::ta2) |
+        (1 << Registers::ta3);
 
     // We use this constant to save registers when entering functions. This
     // is why $ra is added here even though it is not "Non Volatile".