diff --git a/Makefile.am b/Makefile.am
index 6adf9d4f..10b0500d 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -54,6 +54,7 @@ libcoap_@LIBCOAP_API_VERSION@_la_SOURCES = \
   src/coap_io.c \
   src/coap_tinydtls.c \
   src/coap_event.c \
+  src/coap_openssl.c \
   src/coap_time.c \
   src/debug.c \
   src/encode.c \