diff --git a/Makefile.am b/Makefile.am
index 49c254d..288ac61 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -12,7 +12,7 @@
 
 libwritefrudatadir = ${libdir}
 libwritefrudata_LTLIBRARIES = libwritefrudata.la
-libwritefrudata_la_SOURCES = frup.c writefrudata.cpp
+libwritefrudata_la_SOURCES = frup.cpp writefrudata.cpp
 libwritefrudata_la_LDFLAGS = $(SYSTEMD_LIBS) $(libmapper_LIBS) -version-info 1:0:0 -shared
 libwritefrudata_la_CXXFLAGS = $(SYSTEMD_CFLAGS) $(libmapper_CFLAGS)