@@ -145,11 +145,11 @@
 	SSL *ssl;               /* Struct for SSL processing */
 	SSL_CTX *ctx;           /* SSL Context */
 	BIO *bio;               /* Struct for SSL processing */
 	BIO *p_bio;             /* Parent BIO (that is layered on Tcl_Channel) */
 
-	char *err;
+	const char *err;
 } State;
 
 #ifdef USE_TCL_STUBS
 #ifndef Tcl_StackChannel
 #error "Unable to compile on this version of Tcl"
@@ -169,23 +169,30 @@
 # else
 #   define TCL_UNUSED(T) T JOIN(dummy, __LINE__)
 # endif
 #endif
 
+#if (TCL_MAJOR_VERSION < 9) && defined(TCL_MINOR_VERSION) && (TCL_MINOR_VERSION < 7) && !defined(Tcl_Size)
+#   define Tcl_Size int
+#endif
 
 /*
  * Forward declarations
  */
 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);
+#if TCL_MAJOR_VERSION > 8
 void            Tls_Free(void *blockPtr);
+#else
+void            Tls_Free(char *blockPtr);
+#endif
 void            Tls_Clean(State *statePtr);
 int             Tls_WaitForConnect(State *statePtr, int *errorCodePtr, int handshakeFailureIsPermanent);
 
 BIO             *BIO_new_tcl(State* statePtr, int flags);
 
 #define PTR2INT(x) ((int) ((intptr_t) (x)))
 
 #endif /* _TLSINT_H */