diff -Nru sslsplit-0.5.5/debian/patches/openssl3.patch sslsplit-0.5.5/debian/patches/openssl3.patch
--- sslsplit-0.5.5/debian/patches/openssl3.patch	1969-12-31 16:00:00.000000000 -0800
+++ sslsplit-0.5.5/debian/patches/openssl3.patch	2021-12-08 14:23:54.000000000 -0800
@@ -0,0 +1,66 @@
+Description: Compatibility with OpenSSL 3
+ ERR_GET_FUNC() no longer exists in OpenSSL 3, so drop references to it.
+Author: Steve Langasek <steve.langasek@ubuntu.com>
+Last-Update: 2021-12-08
+Forwarded: no
+
+Index: sslsplit-0.5.5/pxyconn.c
+===================================================================
+--- sslsplit-0.5.5.orig/pxyconn.c
++++ sslsplit-0.5.5/pxyconn.c
+@@ -2188,7 +2188,7 @@
+ 			/* these can happen due to client cert auth,
+ 			 * only log error if debugging is activated */
+ 			log_dbg_printf("Error from %s bufferevent: "
+-			               "%i:%s %lu:%i:%s:%i:%s:%i:%s\n",
++			               "%i:%s %lu:%i:%s:%i:%s:%s\n",
+ 			               (bev == ctx->src.bev) ? "src" : "dst",
+ 			               errno,
+ 			               errno ? strerror(errno) : "-",
+@@ -2199,24 +2199,22 @@
+ 			               ERR_GET_LIB(sslerr),
+ 			               sslerr ?
+ 			               ERR_lib_error_string(sslerr) : "-",
+-			               ERR_GET_FUNC(sslerr),
+ 			               sslerr ?
+ 			               ERR_func_error_string(sslerr) : "-");
+ 			while ((sslerr = bufferevent_get_openssl_error(bev))) {
+ 				log_dbg_printf("Additional SSL error: "
+-				               "%lu:%i:%s:%i:%s:%i:%s\n",
++				               "%lu:%i:%s:%i:%s:%s\n",
+ 				               sslerr,
+ 				               ERR_GET_REASON(sslerr),
+ 				               ERR_reason_error_string(sslerr),
+ 				               ERR_GET_LIB(sslerr),
+ 				               ERR_lib_error_string(sslerr),
+-				               ERR_GET_FUNC(sslerr),
+ 				               ERR_func_error_string(sslerr));
+ 			}
+ 		} else {
+ 			/* real errors */
+ 			log_err_printf("Error from %s bufferevent: "
+-			               "%i:%s %lu:%i:%s:%i:%s:%i:%s\n",
++			               "%i:%s %lu:%i:%s:%i:%s:%s\n",
+ 			               (bev == ctx->src.bev) ? "src" : "dst",
+ 			               errno,
+ 			               errno ? strerror(errno) : "-",
+@@ -2227,18 +2225,16 @@
+ 			               ERR_GET_LIB(sslerr),
+ 			               sslerr ?
+ 			               ERR_lib_error_string(sslerr) : "-",
+-			               ERR_GET_FUNC(sslerr),
+ 			               sslerr ?
+ 			               ERR_func_error_string(sslerr) : "-");
+ 			while ((sslerr = bufferevent_get_openssl_error(bev))) {
+ 				log_err_printf("Additional SSL error: "
+-				               "%lu:%i:%s:%i:%s:%i:%s\n",
++				               "%lu:%i:%s:%i:%s:%s\n",
+ 				               sslerr,
+ 				               ERR_GET_REASON(sslerr),
+ 				               ERR_reason_error_string(sslerr),
+ 				               ERR_GET_LIB(sslerr),
+ 				               ERR_lib_error_string(sslerr),
+-				               ERR_GET_FUNC(sslerr),
+ 				               ERR_func_error_string(sslerr));
+ 			}
+ 		}
diff -Nru sslsplit-0.5.5/debian/patches/series sslsplit-0.5.5/debian/patches/series
--- sslsplit-0.5.5/debian/patches/series	2019-08-31 03:41:21.000000000 -0700
+++ sslsplit-0.5.5/debian/patches/series	2021-12-08 14:22:20.000000000 -0800
@@ -1 +1,2 @@
 0001-Use-pkg-config-to-determine-linker-flags-for-test-pr.patch
+openssl3.patch