diff --git a/man2/lseek.2 b/man2/lseek.2
index 460d31750..6a5ef6cd2 100644
--- a/man2/lseek.2
+++ b/man2/lseek.2
@@ -237,6 +237,10 @@ See
 for a discussion of the relationship between file descriptors,
 open file descriptions, and files.
 
+The
+.I off_t
+data type is a signed integer data type specified by POSIX.1.
+
 Some devices are incapable of seeking and POSIX does not specify which
 devices must support
 .BR lseek ().