diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index e093fb4..0695030 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -804,8 +804,10 @@
         fi
     fi
 
-    # check server exit code
-    if [ $SRV_RET != 0 ]; then
+    # Check server exit code (only for Mbed TLS: GnuTLS and OpenSSL don't
+    # exit with status 0 when interrupted by a signal, and we don't really
+    # care anyway), in case e.g. the server reports a memory leak.
+    if [ $SRV_RET != 0 ] && is_polar "$SRV_CMD"; then
         fail "Server exited with status $SRV_RET"
         return
     fi