diff --git a/serial.c b/serial.c
index f7d8e5e..e4e911d 100644
--- a/serial.c
+++ b/serial.c
@@ -181,7 +181,10 @@
 	msg_pdbg("Baud rate is %ld.\n", dcb.BaudRate);
 #else
 	struct termios wanted, observed;
-	fcntl(fd, F_SETFL, 0);
+	if (fcntl(fd, F_SETFL, 0) != 0) {
+		msg_perr_strerror("Could not clear serial port mode: ");
+		return 1;
+	}
 	if (tcgetattr(fd, &observed) != 0) {
 		msg_perr_strerror("Could not fetch original serial port configuration: ");
 		return 1;
@@ -419,14 +422,21 @@
 		return -1;
 	}
 	if(!SetCommTimeouts(sp_fd, &newTimeout)) {
+		msg_perr_strerror("Could not set serial port timeout settings: ");
+		return -1;
+	}
 #else
 	ssize_t rv;
 	const int flags = fcntl(sp_fd, F_GETFL);
-	if (fcntl(sp_fd, F_SETFL, flags | O_NONBLOCK) != 0) {
-#endif
-		msg_perr_strerror("Could not set serial port timeout settings %s");
+	if (flags == -1) {
+		msg_perr_strerror("Could not get serial port mode: ");
 		return -1;
 	}
+	if (fcntl(sp_fd, F_SETFL, flags | O_NONBLOCK) != 0) {
+		msg_perr_strerror("Could not set serial port mode to non-blocking: ");
+		return -1;
+	}
+#endif
 
 	int i;
 	int rd_bytes = 0;
@@ -458,12 +468,15 @@
 	/* restore original blocking behavior */
 #ifdef _WIN32
 	if (!SetCommTimeouts(sp_fd, &oldTimeout)) {
-#else
-	if (fcntl(sp_fd, F_SETFL, flags) != 0) {
-#endif
-		msg_perr_strerror("Could not restore serial port timeout settings: %s\n");
+		msg_perr_strerror("Could not restore serial port timeout settings: ");
 		ret = -1;
 	}
+#else
+	if (fcntl(sp_fd, F_SETFL, flags) != 0) {
+		msg_perr_strerror("Could not restore serial port mode to blocking: ");
+		ret = -1;
+	}
+#endif
 	return ret;
 }
 
@@ -495,7 +508,14 @@
 #else
 	ssize_t rv;
 	const int flags = fcntl(sp_fd, F_GETFL);
-	fcntl(sp_fd, F_SETFL, flags | O_NONBLOCK);
+	if (flags == -1) {
+		msg_perr_strerror("Could not get serial port mode: ");
+		return -1;
+	}
+	if (fcntl(sp_fd, F_SETFL, flags | O_NONBLOCK) != 0) {
+		msg_perr_strerror("Could not set serial port mode to non-blocking: ");
+		return -1;
+	}
 #endif
 
 	int i;
@@ -531,10 +551,13 @@
 #ifdef _WIN32
 	if (!SetCommTimeouts(sp_fd, &oldTimeout)) {
 		msg_perr_strerror("Could not restore serial port timeout settings: ");
-#else
-	if (fcntl(sp_fd, F_SETFL, flags) != 0) {
-#endif
 		return -1;
 	}
+#else
+	if (fcntl(sp_fd, F_SETFL, flags) != 0) {
+		msg_perr_strerror("Could not restore serial port blocking behavior: ");
+		return -1;
+	}
+#endif
 	return ret;
 }