diff --git a/TODO b/TODO
index 3a3bab29fcc6fa3fcc73b9f5c69dabaa3d650a0c..1b789389beae63121707991cc4c6ed447f1d73f7 100644
--- a/TODO
+++ b/TODO
@@ -37,7 +37,7 @@ Tasks
    - Get rid of static variables inside functions.
    - Coalesce hash and checksum functions.
    - Split modstatdb_rw into mode and flags.
-   - Move fd function out of mlib.
+   - Move fd function out of mustlib.
    - Cleanup status chars -> strings hardcoded mappings all over the place.
      (Fix tied field enum with its dselect description (pkgdisplay.cc))
    - Refactor src/unpack.c.
diff --git a/lib/dpkg/Makefile.am b/lib/dpkg/Makefile.am
index 97a8dbfa60381c22a662a65ba9ce770c19669276..5b33351e562907c2087ac86a6265101109410109 100644
--- a/lib/dpkg/Makefile.am
+++ b/lib/dpkg/Makefile.am
@@ -89,7 +89,7 @@ libdpkg_la_SOURCES = \
 	i18n.c i18n.h \
 	log.c \
 	meminfo.c \
-	mlib.c \
+	mustlib.c \
 	namevalue.c \
 	nfmalloc.c \
 	options.c \
diff --git a/lib/dpkg/dpkg.h b/lib/dpkg/dpkg.h
index 463f8296da20dbb5360521031e8846159af3d0fb..d2389a1eb73fb9d0b7ccf22c90a6acb4dea802a8 100644
--- a/lib/dpkg/dpkg.h
+++ b/lib/dpkg/dpkg.h
@@ -135,7 +135,7 @@ void cu_closedir(int argc, void **argv);
 void cu_closefd(int argc, void **argv);
 void cu_filename(int argc, void **argv);
 
-/*** from mlib.c ***/
+/*** from mustlib.c ***/
 
 void setcloexec(int fd, const char *fn);
 void *m_malloc(size_t);
diff --git a/lib/dpkg/mlib.c b/lib/dpkg/mustlib.c
similarity index 97%
rename from lib/dpkg/mlib.c
rename to lib/dpkg/mustlib.c
index d508b036aa2dddc2f2885c27621a861f31e6c21e..52d97527b8d74cf042386007777e3bbc7dbe06a0 100644
--- a/lib/dpkg/mlib.c
+++ b/lib/dpkg/mustlib.c
@@ -1,6 +1,6 @@
 /*
  * libdpkg - Debian packaging suite library routines
- * mlib.c - ‘must’ library: routines will succeed or longjmp
+ * mustlib.c - ‘must’ library: routines will succeed or longjmp
  *
  * Copyright © 1994,1995 Ian Jackson <ijackson@chiark.greenend.org.uk>
  * Copyright © 2006-2013, 2015 Guillem Jover <guillem@debian.org>
diff --git a/po/POTFILES.in b/po/POTFILES.in
index 4008a3abf561ebac2d2738dd4e5cea3e1fd4bd00..b38797ad787cbdb52b57c285c19478154ff5e9cc 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -34,7 +34,7 @@ lib/dpkg/fsys-hash.c
 lib/dpkg/glob.c
 lib/dpkg/i18n.c
 lib/dpkg/log.c
-lib/dpkg/mlib.c
+lib/dpkg/mustlib.c
 lib/dpkg/namevalue.c
 lib/dpkg/nfmalloc.c
 lib/dpkg/options-parsers.c