diff --git a/src/modules/dataman/dataman.c b/src/modules/dataman/dataman.c
index e48b0b5c89..3dd443621a 100644
--- a/src/modules/dataman/dataman.c
+++ b/src/modules/dataman/dataman.c
@@ -672,12 +672,7 @@ task_main(int argc, char *argv[])
 	}
 
 	/* Open or create the data manager file */
-	g_task_fd = open(k_data_manager_device_path, O_RDWR | O_CREAT | O_BINARY
-#ifdef __PX4_LINUX
-			// Open with read/write permission for user
-			, S_IRUSR | S_IWUSR
-#endif
-			);
+	g_task_fd = open(k_data_manager_device_path, O_RDWR | O_CREAT | O_BINARY, PX4_O_MODE_666);
 
 	if (g_task_fd < 0) {
 		warnx("Could not open data manager file %s", k_data_manager_device_path);
diff --git a/src/modules/mavlink/mavlink_ftp.cpp b/src/modules/mavlink/mavlink_ftp.cpp
index 6756b9dcbc..c074d1dde6 100644
--- a/src/modules/mavlink/mavlink_ftp.cpp
+++ b/src/modules/mavlink/mavlink_ftp.cpp
@@ -455,7 +455,8 @@ MavlinkFTP::_workOpen(PayloadHeader* payload, int oflag)
 	}
 	fileSize = st.st_size;
 
-	int fd = ::open(filename, oflag);
+	// Set mode to 666 incase oflag has O_CREAT
+	int fd = ::open(filename, oflag, PX4_O_MODE_666);
 	if (fd < 0) {
 		return kErrFailErrno;
 	}
diff --git a/src/modules/sdlog2/sdlog2.c b/src/modules/sdlog2/sdlog2.c
index f35963d885..270804075e 100644
--- a/src/modules/sdlog2/sdlog2.c
+++ b/src/modules/sdlog2/sdlog2.c
@@ -505,7 +505,7 @@ int open_log_file()
 		}
 	}
 
-	int fd = open(log_file_path, O_CREAT | O_WRONLY | O_DSYNC, 0x0777);
+	int fd = open(log_file_path, O_CREAT | O_WRONLY | O_DSYNC, PX4_O_MODE_666);
 
 	if (fd < 0) {
 		mavlink_and_console_log_critical(mavlink_fd, "[sdlog2] failed opening: %s", log_file_name);
diff --git a/src/modules/systemlib/param/param.c b/src/modules/systemlib/param/param.c
index 1bf986753d..24bc9e73a6 100644
--- a/src/modules/systemlib/param/param.c
+++ b/src/modules/systemlib/param/param.c
@@ -728,7 +728,7 @@ param_save_default(void)
 	const char *filename = param_get_default_file();
 
 	/* write parameters to temp file */
-	fd = PARAM_OPEN(filename, O_WRONLY | O_CREAT, 0x777);
+	fd = PARAM_OPEN(filename, O_WRONLY | O_CREAT, PX4_O_MODE_666);
 
 	if (fd < 0) {
 		warn("failed to open param file: %s", filename);
diff --git a/src/platforms/px4_defines.h b/src/platforms/px4_defines.h
index ac3b15eb9b..d2cc7c2439 100644
--- a/src/platforms/px4_defines.h
+++ b/src/platforms/px4_defines.h
@@ -107,6 +107,11 @@ typedef param_t px4_param_t;
 
 #define PX4_ISFINITE(x) isfinite(x)
 
+// mode for open with O_CREAT
+#define PX4_O_MODE_777 0777
+#define PX4_O_MODE_666 0666
+#define PX4_O_MODE_600 0600
+
 #ifndef PRIu64
 #define PRIu64 "llu"
 #endif
@@ -119,6 +124,12 @@ typedef param_t px4_param_t;
 // Flag is meaningless on Linux
 #define O_BINARY 0
 
+// mode for open with O_CREAT
+#define PX4_O_MODE_777 (S_IRWXU | S_IRWXG | S_IRWXO)
+#define PX4_O_MODE_666 (S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH )
+#define PX4_O_MODE_600 (S_IRUSR | S_IWUSR)
+
+
 // NuttX _IOC is equivalent to Linux _IO
 #define _PX4_IOC(x,y) _IO(x,y)
 
diff --git a/src/systemcmds/param/param.c b/src/systemcmds/param/param.c
index 1609ddcf6a..4aa1d185fd 100644
--- a/src/systemcmds/param/param.c
+++ b/src/systemcmds/param/param.c
@@ -202,7 +202,7 @@ static int
 do_save(const char *param_file_name)
 {
 	/* create the file */
-	int fd = open(param_file_name, O_WRONLY | O_CREAT, 0x777);
+	int fd = open(param_file_name, O_WRONLY | O_CREAT, PX4_O_MODE_666);
 
 	if (fd < 0) {
 		warn("opening '%s' failed", param_file_name);
diff --git a/src/systemcmds/tests/test_file2.c b/src/systemcmds/tests/test_file2.c
index 2e7b5c184f..6adaa7709b 100644
--- a/src/systemcmds/tests/test_file2.c
+++ b/src/systemcmds/tests/test_file2.c
@@ -73,7 +73,7 @@ static void test_corruption(const char *filename, uint32_t write_chunk, uint32_t
 	       filename, (unsigned)write_chunk, (unsigned)write_size);
 
 	uint32_t ofs = 0;
-	int fd = open(filename, O_CREAT | O_RDWR | O_TRUNC);
+	int fd = open(filename, O_CREAT | O_RDWR | O_TRUNC, PX4_O_MODE_666);
 
 	if (fd == -1) {
 		perror(filename);
diff --git a/src/systemcmds/tests/test_mount.c b/src/systemcmds/tests/test_mount.c
index 107d616b6c..2634965d28 100644
--- a/src/systemcmds/tests/test_mount.c
+++ b/src/systemcmds/tests/test_mount.c
@@ -163,7 +163,7 @@ test_mount(int argc, char *argv[])
 	} else {
 
 		/* this must be the first iteration, do something */
-		cmd_fd = open(cmd_filename, O_TRUNC | O_WRONLY | O_CREAT);
+		cmd_fd = open(cmd_filename, O_TRUNC | O_WRONLY | O_CREAT, PX4_O_MODE_666);
 
 		warnx("First iteration of file test\n");
 	}