Index: configure.ac
==================================================================
--- configure.ac
+++ configure.ac
@@ -1,10 +1,9 @@
 #!/bin/bash -norc
 dnl	This file is an input file used by the GNU "autoconf" program to
 dnl	generate the file "configure", which is run during Tcl installation
 dnl	to configure the system for the local environment.
-
 
 #-----------------------------------------------------------------------
 # This is the configure.ac for the TclTLS extension.  The only places you
 # should need to modify this file are marked by the string __CHANGE__.
 #-----------------------------------------------------------------------

Index: generic/tls.c
==================================================================
--- generic/tls.c
+++ generic/tls.c
@@ -2188,17 +2188,20 @@
 	res = SSL_get_signature_nid(statePtr->ssl, &nid);
     }
     if (!res) {nid = 0;}
     LAPPEND_STR(interp, objPtr, "signatureHashAlgorithm", OBJ_nid2ln(nid), -1);
 
+    /* Added in OpenSSL 1.1.1a */
+#if OPENSSL_VERSION_NUMBER > 0x10101000L
     if (objc == 2) {
 	res = SSL_get_peer_signature_type_nid(statePtr->ssl, &nid);
     } else {
 	res = SSL_get_signature_type_nid(statePtr->ssl, &nid);
     }
     if (!res) {nid = 0;}
     LAPPEND_STR(interp, objPtr, "signatureType", OBJ_nid2ln(nid), -1);
+#endif
 
     Tcl_SetObjResult(interp, objPtr);
     return TCL_OK;
 }