@synchronized doesn't work in static library

Question

For some reason, when I try to use @synchronized in a static library for the iPhone, I get an error in the project that uses it:

Undefined symbols:
  "___restore_vfp_d8_d15_regs", referenced from:
      -[GVInbox addConversation:] in libGVKit.a(GVInbox.o)
  "___save_vfp_d8_d15_regs", referenced from:
      -[GVInbox addConversation:] in libGVKit.a(GVInbox.o)
ld: symbol(s) not found
collect2: ld returned 1 exit status