1 files changed, 9 insertions, 3 deletions

diff --git a/src/openssl.c b/src/openssl.c
index 2b0cb88..2dee037 100644
--- a/src/openssl.c
+++ b/src/openssl.c
@@ -33,7 +33,7 @@
 #include <math.h>         /* INFINITY fabs(3) floor(3) frexp(3) fmod(3) round(3) isfinite(3) */
 #include <time.h>         /* struct tm time_t strptime(3) time(2) */
 #include <ctype.h>        /* tolower(3) */
-#include <errno.h>        /* errno */
+#include <errno.h>        /* ENOMEM errno */
 
 #include <sys/types.h>    /* ssize_t pid_t */
 #if !defined __sun && !defined _AIX
@@ -4554,9 +4554,15 @@ static int sx_setAlpnProtos(lua_State *L) {
 done:
         luaL_pushresult(&B);
         tmp = lua_tolstring(L, -1, &len);
+
+        /* OpenSSL 1.0.2 doesn't update the error stack on failure. */
+        ERR_clear_error();
         if (0 != SSL_CTX_set_alpn_protos(ctx, (const unsigned char*)tmp, len)) {
-                lua_pushnil(L);
-                return 1;
+                if (!ERR_peek_error()) {
+                        return luaL_error(L, "unable to set ALPN protocols: %s", xstrerror(ENOMEM));
+                } else {
+                        return throwssl(L, "ssl.context:setAlpnProtos");
+                }
         }
 
         lua_pushboolean(L, 1);