diff --git a/lib/modules/SSL.pmod/pem.pmod b/lib/modules/SSL.pmod/pem.pmod
index bdbe86f7a0e25427d69d638287968a39064fdfa7..57e6fe9e12dca1e2f3a52203b92eb983319aa17c 100644
--- a/lib/modules/SSL.pmod/pem.pmod
+++ b/lib/modules/SSL.pmod/pem.pmod
@@ -3,6 +3,8 @@
  * Primitive PEM decoder. (Extracted from roxen/server/protocols/ssl3.pike).
  */
 
+#error SSL.pem is obsolete! Use Tools.PEM instead.
+
 object begin_pem = Regexp("-----BEGIN (.*)----- *$");
 object end_pem = Regexp("-----END (.*)----- *$");