diff --git a/include/mcl/op.hpp b/include/mcl/op.hpp
index c660fc6..9638f25 100644
--- a/include/mcl/op.hpp
+++ b/include/mcl/op.hpp
@@ -97,6 +97,7 @@ typedef uint64_t Unit;
 const size_t UnitBitSize = sizeof(Unit) * 8;
 
 const size_t maxOpUnitSize = (MCL_MAX_BIT_SIZE + UnitBitSize - 1) / UnitBitSize;
+#define MCL_MAX_UNIT_SIZE ((MCL_MAX_BIT_SIZE + CYBOZU_OS_BIT - 1) / CYBOZU_OS_BIT)
 
 struct FpGenerator;
 struct Op;
diff --git a/src/fp.cpp b/src/fp.cpp
index a8015fd..2cce788 100644
--- a/src/fp.cpp
+++ b/src/fp.cpp
@@ -422,28 +422,30 @@ void Op::init(const std::string& mstr, size_t maxBitSize, Mode mode)
 	case 2:  setOp<2>(*this, mode); break;
 	case 3:  setOp<3>(*this, mode); break;
 	case 4:  setOp<4>(*this, mode); break; // 256 if 64-bit
+#if MCL_MAX_UNIT_SIZE >= 6
 	case 5:  setOp<5>(*this, mode); break;
 	case 6:  setOp<6>(*this, mode); break;
+#endif
+#if MCL_MAX_UNIT_SIZE >= 9
 	case 7:  setOp<7>(*this, mode); break;
 	case 8:  setOp<8>(*this, mode); break;
-	case 9:  setOp<9>(*this, mode); break; // 576 if 64-bit
-#if CYBOZU_OS_BIT == 32 || MCL_MAX_BIT_SIZE >= 768
+	case 9:  setOp<9>(*this, mode); break; // 521 if 64-bit
+#endif
+#if MCL_MAX_UNIT_SIZE >= 12
 	case 10: setOp<10>(*this, mode); break;
 	case 11: setOp<11>(*this, mode); break;
 	case 12: setOp<12>(*this, mode); break; // 768 if 64-bit
 #endif
-#if CYBOZU_OS_BIT == 32
+#if MCL_MAX_UNIT_SIZE >= 14
 	case 13: setOp<13>(*this, mode); break;
 	case 14: setOp<14>(*this, mode); break;
-	case 15: setOp<15>(*this, mode); break;
-	case 16: setOp<16>(*this, mode); break;
-	case 17: setOp<17>(*this, mode); break; // 544 if 32-bit
 #endif
-#if CYBOZU_OS_BIT == 64 && MCL_MAX_BIT_SIZE == 1024
-	case 13: setOp<13>(*this, mode); break;
-	case 14: setOp<14>(*this, mode); break;
+#if MCL_MAX_UNIT_SIZE >= 16
 	case 15: setOp<15>(*this, mode); break;
-	case 16: setOp<16>(*this, mode); break;
+	case 16: setOp<16>(*this, mode); break; // 1024 if 64-bit
+#endif
+#if MCL_MAX_UNIT_SIZE >= 17
+	case 17: setOp<17>(*this, mode); break; // 521 if 32-bit
 #endif
 	default:
 		throw cybozu::Exception("Op::init:not:support") << N << mstr;
diff --git a/src/low_func_llvm.hpp b/src/low_func_llvm.hpp
index 294c022..a96f3fa 100644
--- a/src/low_func_llvm.hpp
+++ b/src/low_func_llvm.hpp
@@ -54,30 +54,37 @@ MCL_DEF_LLVM_FUNC(1)
 MCL_DEF_LLVM_FUNC(2)
 MCL_DEF_LLVM_FUNC(3)
 MCL_DEF_LLVM_FUNC(4)
+#if MCL_MAX_UNIT_SIZE >= 6
 MCL_DEF_LLVM_FUNC(5)
 MCL_DEF_LLVM_FUNC(6)
+#endif
+#if MCL_MAX_UNIT_SIZE >= 9
 MCL_DEF_LLVM_FUNC(7)
 MCL_DEF_LLVM_FUNC(8)
 MCL_DEF_LLVM_FUNC(9)
-#if CYBOZU_OS_BIT == 32 || MCL_MAX_BIT_SIZE >= 768
+#endif
+#if MCL_MAX_UNIT_SIZE >= 12
 MCL_DEF_LLVM_FUNC(10)
 MCL_DEF_LLVM_FUNC(11)
 MCL_DEF_LLVM_FUNC(12)
 #endif
-#if CYBOZU_OS_BIT == 32
+#if MCL_MAX_UNIT_SIZE >= 14
 MCL_DEF_LLVM_FUNC(13)
 MCL_DEF_LLVM_FUNC(14)
+#endif
+#if MCL_MAX_UNIT_SIZE >= 16
 MCL_DEF_LLVM_FUNC(15)
+#if CYBOZU_OS_BIT == 32
 MCL_DEF_LLVM_FUNC(16)
-MCL_DEF_LLVM_FUNC(17)
-#endif
-#if CYBOZU_OS_BIT == 64 && MCL_MAX_BIT_SIZE == 1024
-MCL_DEF_LLVM_FUNC(14)
-//MCL_DEF_LLVM_FUNC(16)
+#else
 /// QQQ : check speed
 template<>const void3u MontRed<16, Ltag>::f = &mcl_fp_montRed16L;
 template<>const void3u MontRed<16, LBMI2tag>::f = &mcl_fp_montRed16Lbmi2;
 #endif
+#endif
+#if MCL_MAX_UNIT_SIZE >= 17
+MCL_DEF_LLVM_FUNC(17)
+#endif
 
 } } // mcl::fp
 
diff --git a/src/proto.hpp b/src/proto.hpp
index ea78a4b..380e38e 100644
--- a/src/proto.hpp
+++ b/src/proto.hpp
@@ -41,26 +41,30 @@ MCL_FP_DEF_FUNC(1)
 MCL_FP_DEF_FUNC(2)
 MCL_FP_DEF_FUNC(3)
 MCL_FP_DEF_FUNC(4)
+#if MCL_MAX_UNIT_SIZE >= 6
 MCL_FP_DEF_FUNC(5)
 MCL_FP_DEF_FUNC(6)
+#endif
+#if MCL_MAX_UNIT_SIZE >= 9
 MCL_FP_DEF_FUNC(7)
 MCL_FP_DEF_FUNC(8)
 MCL_FP_DEF_FUNC(9)
-#if CYBOZU_OS_BIT == 32 || MCL_MAX_BIT_SIZE >= 768
+#endif
+#if MCL_MAX_UNIT_SIZE >= 12
 MCL_FP_DEF_FUNC(10)
 MCL_FP_DEF_FUNC(11)
 MCL_FP_DEF_FUNC(12)
 #endif
-#if CYBOZU_OS_BIT == 32
+#if MCL_MAX_UNIT_SIZE >= 14
 MCL_FP_DEF_FUNC(13)
 MCL_FP_DEF_FUNC(14)
+#endif
+#if MCL_MAX_UNIT_SIZE >= 16
 MCL_FP_DEF_FUNC(15)
 MCL_FP_DEF_FUNC(16)
-MCL_FP_DEF_FUNC(17)
 #endif
-#if CYBOZU_OS_BIT == 64 && MCL_MAX_BIT_SIZE == 1024
-MCL_FP_DEF_FUNC(14)
-MCL_FP_DEF_FUNC(16)
+#if MCL_MAX_UNIT_SIZE >= 17
+MCL_FP_DEF_FUNC(17)
 #endif
 
 MCL_FP_DEF_FUNC_SPECIAL(L)