diff --git a/src/FDM/SP/Makefile.am b/src/FDM/SP/Makefile.am
index 3f84367f0..7271c3c69 100644
--- a/src/FDM/SP/Makefile.am
+++ b/src/FDM/SP/Makefile.am
@@ -3,6 +3,9 @@ noinst_LIBRARIES = libSPFDM.a
 
 libSPFDM_a_SOURCES = \
 	ADA.cxx ADA.hxx \
-	ACMS.cxx ACMS.hxx 
+	ACMS.cxx ACMS.hxx \
+	Balloon.cxx Balloon.h \
+	BalloonSim.cpp BalloonSim.h \
+	MagicCarpet.cxx MagicCarpet.hxx
 
 INCLUDES = -I$(top_srcdir) -I$(top_srcdir)/src