diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9172f66..df46bd1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -249,6 +249,7 @@ parse_Makefile_am(${CMAKE_CURRENT_SOURCE_DIR}/src/dec "${WEBP_SRCS}")
 parse_Makefile_am(${CMAKE_CURRENT_SOURCE_DIR}/src/demux "${WEBP_SRCS}")
 parse_Makefile_am(${CMAKE_CURRENT_SOURCE_DIR}/src/dsp "${WEBP_SRCS}")
 parse_Makefile_am(${CMAKE_CURRENT_SOURCE_DIR}/src/enc "${WEBP_SRCS}")
+parse_Makefile_am(${CMAKE_CURRENT_SOURCE_DIR}/src/mux "${WEBP_SRCS}")
 parse_Makefile_am(${CMAKE_CURRENT_SOURCE_DIR}/src/utils "${WEBP_SRCS}")
 
 # Remove the files specific to SIMD we don't user.