diff --git a/Makefile b/Makefile
index c124150..c356c42 100644
--- a/Makefile
+++ b/Makefile
@@ -335,8 +335,7 @@ ecdsa-wasm:
 bin/emu:
 	$(CXX) -g -o $@ src/fp.cpp src/bn_c256.cpp test/bn_c256_test.cpp -DMCL_DONT_USE_XBYAK -DMCL_DONT_USE_OPENSSL -DMCL_USE_VINT -DMCL_SIZEOF_UNIT=8 -DMCL_VINT_64BIT_PORTABLE -DMCL_VINT_FIXED_BUFFER -DMCL_MAX_BIT_SIZE=256 -I./include
 bin/pairing_c_min.exe: sample/pairing_c.c include/mcl/vint.hpp src/fp.cpp include/mcl/bn.hpp
-#	$(CXX) -o $@ sample/pairing_c.c src/fp.cpp src/bn_c256.cpp -O2 -g -I./include -fno-exceptions -fno-rtti -fno-threadsafe-statics -DMCL_DONT_USE_XBYAK -DMCL_DONT_USE_OPENSSL -DMCL_USE_VINT -DMCL_SIZEOF_UNIT=8 -DMCL_VINT_FIXED_BUFFER -DCYBOZU_DONT_USE_EXCEPTION -DCYBOZU_DONT_USE_STRING -DMCL_DONT_USE_CSPRNG -DMCL_MAX_BIT_SIZE=256 -DMCL_VINT_64BIT_PORTABLE -DNDEBUG -pg
-	$(CXX) -o $@ sample/pairing_c.c src/fp.cpp src/bn_c256.cpp -O2 -g -I./include -fno-threadsafe-statics -DMCL_DONT_USE_XBYAK -DMCL_DONT_USE_OPENSSL -DMCL_USE_VINT -DMCL_SIZEOF_UNIT=8 -DMCL_VINT_FIXED_BUFFER -DMCL_DONT_USE_CSPRNG -DMCL_MAX_BIT_SIZE=256 -DMCL_VINT_64BIT_PORTABLE -DNDEBUG
+	$(CXX) -o $@ sample/pairing_c.c src/fp.cpp src/bn_c256.cpp -Og -g -I./include -fno-threadsafe-statics -DMCL_DONT_USE_XBYAK -DMCL_DONT_USE_OPENSSL -DMCL_USE_VINT -DMCL_SIZEOF_UNIT=8 -DMCL_VINT_FIXED_BUFFER -DMCL_MAX_BIT_SIZE=256 -DMCL_VINT_64BIT_PORTABLE #-DNDEBUG -DMCL_DONT_USE_CSPRNG
 
 make_tbl:
 	$(MAKE) ../bls/src/qcoeff-bn254.hpp
diff --git a/include/cybozu/random_generator.hpp b/include/cybozu/random_generator.hpp
index ff4a78d..4a9f071 100644
--- a/include/cybozu/random_generator.hpp
+++ b/include/cybozu/random_generator.hpp
@@ -7,7 +7,9 @@
 	http://opensource.org/licenses/BSD-3-Clause
 */
 
+#ifndef CYBOZU_DONT_USE_EXCEPTION
 #include <cybozu/exception.hpp>
+#endif
 #ifdef _WIN32
 #include <winsock2.h>
 #include <windows.h>
@@ -27,22 +29,6 @@ class RandomGenerator {
 	RandomGenerator(const RandomGenerator&);
 	void operator=(const RandomGenerator&);
 public:
-	uint32_t operator()()
-	{
-		return get32();
-	}
-	uint32_t get32()
-	{
-		uint32_t ret;
-		read(&ret, 1);
-		return ret;
-	}
-	uint64_t get64()
-	{
-		uint64_t ret;
-		read(&ret, 1);
-		return ret;
-	}
 #ifdef _WIN32
 	RandomGenerator()
 		: prov_(0)
@@ -52,10 +38,15 @@ public:
 		for (int i = 0; i < 2; i++) {
 			if (CryptAcquireContext(&prov_, NULL, NULL, PROV_RSA_FULL, flagTbl[i]) != 0) return;
 		}
+#ifdef CYBOZU_DONT_USE_EXCEPTION
+		prov_ = 0;
+#else
 		throw cybozu::Exception("randomgenerator");
+#endif
 	}
 	bool read_inner(void *buf, size_t byteSize)
 	{
+		if (prov_ == 0) return false;
 		return CryptGenRandom(prov_, static_cast<DWORD>(byteSize), static_cast<BYTE*>(buf)) != 0;
 	}
 	~RandomGenerator()
@@ -88,13 +79,6 @@ public:
 		}
 		*pb = true;
 	}
-	template<class T>
-	void read(T *buf, size_t bufNum)
-	{
-		bool b;
-		read(&b, buf, bufNum);
-		if (!b) throw cybozu::Exception("RandomGenerator:read") << bufNum;
-	}
 private:
 	HCRYPTPROV prov_;
 	static const size_t bufSize = 1024;
@@ -105,7 +89,9 @@ private:
 	RandomGenerator()
 		: fp_(::fopen("/dev/urandom", "rb"))
 	{
+#ifndef CYBOZU_DONT_USE_EXCEPTION
 		if (!fp_) throw cybozu::Exception("randomgenerator");
+#endif
 	}
 	~RandomGenerator()
 	{
@@ -121,6 +107,8 @@ private:
 		const size_t byteSize = sizeof(T) * bufNum;
 		*pb = ::fread(buf, 1, (int)byteSize, fp_) == byteSize;
 	}
+#endif
+#ifndef CYBOZU_DONT_USE_EXCEPTION
 	template<class T>
 	void read(T *buf, size_t bufNum)
 	{
@@ -128,6 +116,22 @@ private:
 		read(&b, buf, bufNum);
 		if (!b) throw cybozu::Exception("RandomGenerator:read") << bufNum;
 	}
+	uint32_t get32()
+	{
+		uint32_t ret;
+		read(&ret, 1);
+		return ret;
+	}
+	uint64_t get64()
+	{
+		uint64_t ret;
+		read(&ret, 1);
+		return ret;
+	}
+	uint32_t operator()()
+	{
+		return get32();
+	}
 #endif
 private:
 	FILE *fp_;
diff --git a/sample/pairing_c.c b/sample/pairing_c.c
index 5c2cd22..ac55908 100644
--- a/sample/pairing_c.c
+++ b/sample/pairing_c.c
@@ -11,7 +11,11 @@ int main()
 	char buf[1024];
 	const char *aStr = "123";
 	const char *bStr = "456";
-	mclBn_init(MCL_BN254, MCLBN_FP_UNIT_SIZE);
+	int ret = mclBn_init(MCL_BN254, MCLBN_COMPILED_TIME_VAR);
+	if (ret != 0) {
+		printf("err ret=%d\n", ret);
+		return 1;
+	}
 	mclBnFr a, b, ab;
 	mclBnG1 P, aP;
 	mclBnG2 Q, bQ;