Give everything prototypes (well, everything that's actually used).
diff --git a/crypto/engine/enginetest.c b/crypto/engine/enginetest.c
index c2d0297..cf82f49 100644
--- a/crypto/engine/enginetest.c
+++ b/crypto/engine/enginetest.c
@@ -72,7 +72,7 @@
 #include <openssl/engine.h>
 #include <openssl/err.h>
 
-static void display_engine_list()
+static void display_engine_list(void)
 	{
 	ENGINE *h;
 	int loop;