diff --git a/src/Makefile.am b/src/Makefile.am
index 8623ed8d..aad95fd9 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -87,6 +87,8 @@ libiphreeqc_la_SOURCES=\
 	phreeqcpp/System.h\
 	phreeqcpp/Temperature.cxx\
 	phreeqcpp/Temperature.h\
+	phreeqcpp/Use.cpp\
+	phreeqcpp/Use.h\
 	phreeqcpp/Utils.cxx\
 	phreeqcpp/Utils.h\
 	phreeqcpp/phreeqc/advection.cpp\
diff --git a/unit/GNUmakefile b/unit/GNUmakefile
index 6dde8b40..f25d1a22 100644
--- a/unit/GNUmakefile
+++ b/unit/GNUmakefile
@@ -89,6 +89,7 @@ PPOBJS = \
 	Surface.o \
 	System.o \
 	Temperature.o \
+	Use.o \
 	Utils.o
 
 # phreeqc objs