Tcl extension: check Tcl version?

Is there a recommended way to check if a (binary) Tcl extension
is loaded to the same Tcl version that was used for linking
the extension?

Currently I'm encountering a problem with an extension that
I have built (and linked) with libtk8.3.so and that can be
loaded under wish8.5 as well (without re-bulding, using
package require).  A number of newly provided commands work
well in spite of the version mixture, but others don't, and
wish8.5 crashes when these commands are used.

Is this behavior normal, i.e. should I check that compile-time
version and run-time version are identical? Or does this
indicate some subtle coding problem?

Thanks for any suggestions
Olaf