diff --git a/include/mcl/ec.hpp b/include/mcl/ec.hpp
index ab4d2bc..3fa361a 100644
--- a/include/mcl/ec.hpp
+++ b/include/mcl/ec.hpp
@@ -652,6 +652,17 @@ public:
 	*/
 	void getStr(std::string& str, int ioMode = 0) const
 	{
+		const char *sep = Fp::BaseFp::getIoSeparator();
+		if (ioMode & IoEcProj) {
+			str = '4';
+			str += sep;
+			str += x.getStr(ioMode);
+			str += sep;
+			str += y.getStr(ioMode);
+			str += sep;
+			str += z.getStr(ioMode);
+			return;
+		}
 		EcT P(*this);
 		P.normalize();
 		if (ioMode & IoEcComp) {
@@ -672,7 +683,6 @@ public:
 			str = '0';
 			return;
 		}
-		const char *sep = Fp::BaseFp::getIoSeparator();
 		if (ioMode & IoEcCompY) {
 			str = P.y.isOdd() ? '3' : '2';
 			str += sep;
@@ -734,6 +744,9 @@ public:
 			} else if (c == '2' || c == '3') {
 				bool isYodd = c == '3';
 				getYfromX(y, x, isYodd);
+			} else if (c == '4') {
+				y.readStream(is, ioMode);
+				z.readStream(is, ioMode);
 			} else {
 				throw cybozu::Exception("EcT:readStream:bad format") << c;
 			}
diff --git a/test/ec_test.cpp b/test/ec_test.cpp
index 6cc3255..421979b 100644
--- a/test/ec_test.cpp
+++ b/test/ec_test.cpp
@@ -280,25 +280,25 @@ struct Test {
 			ss >> Q;
 			CYBOZU_TEST_EQUAL(P, Q);
 		}
-		// tight
+		// IoEcComp
 		if (!Ec::isIoEcCompSupported()) return;
 		P.set(x, y);
 		{
-			std::string s = P.getStr(mcl::IoTight);
+			std::string s = P.getStr(mcl::IoEcComp);
 			CYBOZU_TEST_EQUAL(s.size(), Fp::getByteSize());
 			Q.setStr(s, mcl::IoTight);
 			CYBOZU_TEST_EQUAL(P, Q);
 		}
 		{
 			P = -P;
-			std::string s = P.getStr(mcl::IoTight);
+			std::string s = P.getStr(mcl::IoEcComp);
 			CYBOZU_TEST_EQUAL(s.size(), Fp::getByteSize());
 			Q.setStr(s, mcl::IoTight);
 			CYBOZU_TEST_EQUAL(P, Q);
 		}
 		P.clear();
 		{
-			std::string s = P.getStr(mcl::IoTight);
+			std::string s = P.getStr(mcl::IoEcComp);
 			CYBOZU_TEST_EQUAL(s.size(), Fp::getByteSize());
 			CYBOZU_TEST_ASSERT(mcl::fp::isZeroArray(s.c_str(), s.size()));
 			Q.setStr(s, mcl::IoTight);