diff -Nru orig/RSclient/src/Makevars.win patched/RSclient/src/Makevars.win
--- orig/RSclient/src/Makevars.win	2022-11-29 02:53:59.000000000 +0100
+++ patched/RSclient/src/Makevars.win	2023-10-10 09:23:36.377343500 +0200
@@ -1 +1,5 @@
-PKG_LIBS = -lssl -lcrypto -lws2_32 -lgdi32 -lcrypt32 -lz
+ifeq (,$(shell pkg-config --version 2>/dev/null))
+  PKG_LIBS = -lssl -lcrypto -lws2_32 -lgdi32 -lcrypt32 -lz
+else
+  PKG_LIBS = $(shell pkg-config --libs openssl)
+endif