Index: generic/tls.c
==================================================================
--- generic/tls.c
+++ generic/tls.c
@@ -336,11 +336,11 @@
  *	The err field of the currently operative State is set
  *	  to a string describing the SSL negotiation failure reason
  *-------------------------------------------------------------------
  */
 void
-Tls_Error(State *statePtr, char *msg)
+Tls_Error(State *statePtr, const char *msg)
 {
     Tcl_Obj *cmdPtr;
 
     dprintf("Called");
 

Index: generic/tlsIO.c
==================================================================
--- generic/tlsIO.c
+++ generic/tlsIO.c
@@ -234,11 +234,11 @@
 
 		statePtr->flags |= TLS_TCL_HANDSHAKE_FAILED;
 		return -1;
 	case SSL_ERROR_SSL:
 	    dprintf("Got permanent fatal SSL error, aborting immediately");
-		Tls_Error(statePtr, (char *)ERR_reason_error_string(ERR_get_error()));
+		Tls_Error(statePtr, ERR_reason_error_string(ERR_get_error()));
 	    statePtr->flags |= TLS_TCL_HANDSHAKE_FAILED;
 	    *errorCodePtr = ECONNABORTED;
 	    return -1;
 	default:
 	    dprintf("We got a confusing reply: %i", rc);
@@ -253,11 +253,11 @@
 
 	err = SSL_get_verify_result(statePtr->ssl);
 	if (err != X509_V_OK) {
 		dprintf("Invalid certificate, returning in failure");
 
-		Tls_Error(statePtr, (char *)X509_verify_cert_error_string(err));
+		Tls_Error(statePtr, X509_verify_cert_error_string(err));
 		statePtr->flags |= TLS_TCL_HANDSHAKE_FAILED;
 		*errorCodePtr = ECONNABORTED;
 		return -1;
 	}
     }

Index: generic/tlsInt.h
==================================================================
--- generic/tlsInt.h
+++ generic/tlsInt.h
@@ -97,11 +97,11 @@
 #define dprintf(...) if (0) { fprintf(stderr, __VA_ARGS__); }
 #define dprintBuffer(bufferName, bufferLength) /**/
 #define dprintFlags(statePtr) /**/
 #endif
 
-#define TCLTLS_SSL_ERROR(ssl,err) ((char*)ERR_reason_error_string((unsigned long)SSL_get_error((ssl),(err))))
+#define TCLTLS_SSL_ERROR(ssl,err) ERR_reason_error_string((unsigned long)SSL_get_error((ssl),(err)))
 #define GET_ERR_REASON()	ERR_reason_error_string(ERR_get_error())
 
 /* Common list append macros */
 #define LAPPEND_BARRAY(interp, obj, text, value, size) {\
     if (text != NULL) Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(text, -1)); \
@@ -199,11 +199,11 @@
  */
 const Tcl_ChannelType *Tls_ChannelType(void);
 Tcl_Channel     Tls_GetParent(State *statePtr, int maskFlags);
 
 Tcl_Obj        *Tls_NewX509Obj(Tcl_Interp *interp, X509 *cert);
-void            Tls_Error(State *statePtr, char *msg);
+void            Tls_Error(State *statePtr, const char *msg);
 #if TCL_MAJOR_VERSION > 8
 void            Tls_Free(void *blockPtr);
 #else
 void            Tls_Free(char *blockPtr);
 #endif