diff --git a/src/Makefile.am b/src/Makefile.am
index 4c3496ad1..f273f90fe 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -32,6 +32,11 @@ KADEMLIA_SOURCES = \
   ../ed25519/src/verify.cpp
 endif
 
+if ! WITH_OPENSSL
+BUILTIN_CRYPTO_SOURCES = \
+  sha1.cpp
+endif
+
 libtorrent_rasterbar_la_SOURCES = \
   web_connection_base.cpp         \
   alert.cpp                       \
@@ -115,7 +120,6 @@ libtorrent_rasterbar_la_SOURCES = \
   session_settings.cpp            \
   proxy_settings.cpp              \
   settings_pack.cpp               \
-  sha1.cpp                        \
   smart_ban.cpp                   \
   socket_io.cpp                   \
   socket_type.cpp                 \
@@ -148,7 +152,9 @@ libtorrent_rasterbar_la_SOURCES = \
   version.cpp                     \
   file_progress.cpp               \
   \
-  $(KADEMLIA_SOURCES)
+  $(KADEMLIA_SOURCES) \
+  \
+  $(BUILTIN_CRYPTO_SOURCES)
 
 libtorrent_rasterbar_la_LDFLAGS = -version-info $(INTERFACE_VERSION_INFO)
 libtorrent_rasterbar_la_LIBADD = @BOOST_SYSTEM_LIB@ @OPENSSL_LIBS@