If there happens to be need:
— In case of trouble call 911.
— I have money, just in case.

synonym: just in case.

Roget 8: in the circumstances, under the circumstances etc. n., the circumstances, conditions etc. 7; thus, in such wise.    accordingly; that being the case, such being the case, in view of the circumstances; that being so, sith^†, since, seeing that.    as matters stand; as things go, as times go.    conditionally, provided, if, in case; if so, if so be, if it be so; depending on circumstances, in certain circumstances, under certain conditions; if it so happen, if it so turn out; in the event of; in such a contingency, in such a case, in such an event; provisionally, unless, without.    according to circumstances, according to the occasion; as it may happen, as it may turn out, as it may be; as the case may be, as the wind blows; pro re nata [Lat.].    ... show more

Roget 151: eventually; in the event of, in case, just in case; in the course of things; as things, times go; as the world goes, wags; as the tree falls, cat jumps; as it may turn out, happen.