diff --git a/man7/libc.7 b/man7/libc.7
index bc11d1c27..8d0237951 100644
--- a/man7/libc.7
+++ b/man7/libc.7
@@ -64,8 +64,13 @@ In the early to mid 1990s, there was for a while
 a fork of glibc 1.x created by Linux developers who felt that glibc
 development at the time was not sufficing for the needs of Linux.
 Often, this library was referred to (ambiguously) as just "libc".
-Linux libc released major versions 2, 3, 4, and 5
-(as well as many minor versions of those releases).
+Linux libc released major versions 2, 3, 4, and 5,
+as well as many minor versions of those releases.
+Linux libc4 was the last version to use the a.out binary format,
+and the first version to provide (primitive) shared library support.
+Linux libc 5 was the first version to support the ELF binary format;
+this version used the shared library soname
+.IR libc.so.5 .
 For a while,
 Linux libc was the standard C library in many Linux distributions.