diff --git a/src_main/io/pisharedmemory.cpp b/src_main/io/pisharedmemory.cpp
index 1538f401..84d083a0 100644
--- a/src_main/io/pisharedmemory.cpp
+++ b/src_main/io/pisharedmemory.cpp
@@ -109,15 +109,13 @@ bool PISharedMemory::openDevice() {
 	//piCout << PRIVATE->map << PRIVATE->data;
 #endif
 #ifdef LINUX
-	int m = O_RDWR;
-	if (!isWriteable()) m = O_RDONLY;
 	PRIVATE->name = ("/pip_shm_" + path()).toByteArray();
 	PRIVATE->name.push_back(0);
-	int fd = shm_open((const char *)PRIVATE->name.data(), m, 0777);
+	int fd = shm_open((const char *)PRIVATE->name.data(), O_RDWR, 0777);
 	//piCoutObj << "try open" << PICoutManipulators::Hex << fd;
 	if (fd < 0) {
 		//piCoutObj << "shm_open error," << errorString();
-		fd = shm_open((const char *)PRIVATE->name.data(), m | O_CREAT, 0777);
+		fd = shm_open((const char *)PRIVATE->name.data(), O_RDWR | O_CREAT, 0777);
 		//piCoutObj << "try create" << PICoutManipulators::Hex << (m | O_CREAT) << fd;
 		if (fd < 0) {
 			//piCoutObj << "shm_open error," << errorString();
@@ -127,11 +125,9 @@ bool PISharedMemory::openDevice() {
 		ftruncate(fd, dsize);
 		//piCoutObj << "created" << fd;
 	}
-	m = PROT_WRITE;
-	if (!isWriteable()) m = PROT_READ;
-	PRIVATE->data = mmap(0, dsize, m, MAP_SHARED, fd, 0);
+	PRIVATE->data = mmap(0, dsize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 	::close(fd);
-	if (!PRIVATE->data) {
+	if (PRIVATE->data == MAP_FAILED) {
 		piCoutObj << "mmap error," << errorString();
 		return false;
 	}