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