diff --git a/src/lib/src/fwts_acpid.c b/src/lib/src/fwts_acpid.c
index 3107052..c7e5c43 100644
--- a/src/lib/src/fwts_acpid.c
+++ b/src/lib/src/fwts_acpid.c
@@ -77,7 +77,7 @@ char *fwts_acpi_event_read(const int fd, size_t *length, const int timeout)
 	fd_set rfds;
 
 	int ret;
-	size_t n;
+	ssize_t n;
 	size_t size = 0;
 	*length = 0;