diff --git a/3rd_party/libsrp6a-sha512/Makefile.am b/3rd_party/libsrp6a-sha512/Makefile.am
index d304585..c349d8c 100644
--- a/3rd_party/libsrp6a-sha512/Makefile.am
+++ b/3rd_party/libsrp6a-sha512/Makefile.am
@@ -5,8 +5,6 @@
         -I$(top_srcdir) \
         -Wno-incompatible-pointer-types
 
-include_HEADERS = srp.h srp_aux.h cstr.h
-
 AM_CFLAGS = -DHAVE_CONFIG_H
 if HAVE_OPENSSL
 AM_CFLAGS += -DOPENSSL=1 $(openssl_CFLAGS)
@@ -25,7 +23,8 @@
 libsrp6a_sha512_la_SOURCES = \
   t_conv.c t_math.c t_misc.c \
   t_truerand.c cstr.c \
-  srp.c srp6a_sha512_client.c
+  srp.c srp6a_sha512_client.c \
+  srp.h srp_aux.h cstr.h
 if !HAVE_OPENSSL
 libsrp6a_sha512_la_SOURCES += t_sha.c
 endif