diff --git a/app/operations/Makefile.am b/app/operations/Makefile.am
index bcee62ae5d..d5998fd972 100644
--- a/app/operations/Makefile.am
+++ b/app/operations/Makefile.am
@@ -164,6 +164,8 @@ libappoperations_sse4_a_CFLAGS = $(SSE4_1_EXTRA_CFLAGS)
 
 libappoperations_generic_a_SOURCES = $(libappoperations_generic_a_sources)
 
+libappoperations_a_SOURCES =
+
 libappoperations.a: libappoperations-generic.a \
                     libappoperations-sse2.a \
                     libappoperations-sse4.a