diff --git a/Android.mk b/Android.mk
index a0a9eb7f..c36c9574 100644
--- a/Android.mk
+++ b/Android.mk
@@ -35,6 +35,7 @@ LOCAL_SRC_FILES := \
     src/enc/syntax.c \
     src/enc/tree.c \
     src/enc/webpenc.c \
+    src/mux/demux.c \
     src/mux/muxedit.c \
     src/mux/muxinternal.c \
     src/mux/muxread.c \
diff --git a/Makefile.vc b/Makefile.vc
index b81aaea3..09bbe310 100644
--- a/Makefile.vc
+++ b/Makefile.vc
@@ -194,6 +194,7 @@ ENC_OBJS = \
     $(DIROBJ)\enc\webpenc.obj \
 
 MUX_OBJS = \
+    $(DIROBJ)\mux\demux.obj \
     $(DIROBJ)\mux\muxedit.obj \
     $(DIROBJ)\mux\muxinternal.obj \
     $(DIROBJ)\mux\muxread.obj \
diff --git a/makefile.unix b/makefile.unix
index 6f4d0726..163b40da 100644
--- a/makefile.unix
+++ b/makefile.unix
@@ -109,6 +109,7 @@ EX_UTIL_OBJS = \
     examples/example_util.o \
 
 MUX_OBJS = \
+    src/mux/demux.o \
     src/mux/muxedit.o \
     src/mux/muxinternal.o \
     src/mux/muxread.o \
diff --git a/src/mux/Makefile.am b/src/mux/Makefile.am
index bc07f7a6..3beb240e 100644
--- a/src/mux/Makefile.am
+++ b/src/mux/Makefile.am
@@ -2,6 +2,7 @@ AM_CPPFLAGS = -I$(top_srcdir)/src
 lib_LTLIBRARIES = libwebpmux.la
 
 libwebpmux_la_SOURCES =
+libwebpmux_la_SOURCES += demux.c
 libwebpmux_la_SOURCES += muxedit.c
 libwebpmux_la_SOURCES += muxi.h
 libwebpmux_la_SOURCES += muxinternal.c