Ruby on OS X 10.9 Ignoring gems because extensions are not built

Every few days this will happen when doing various things in Ruby CLI (notably, using the knife utility for Chef) on OS X (unable to replicate in other environments; Linux, FreeBSD, etc.): Ignoring bcrypt-3.1.7 because its extensions are not built. Try: gem pristine bcrypt-3.1.7 Ignoring bigdecimal-1.2.5 because its extensions are not built. Try: gem pristine bigdecimal-1.2.5 Ignoring ffi-yajl-1.1.0 because its extensions are not built. Try: gem pristine ffi-yajl-1.1.0 Ignoring gem-wrappers-1.2.5 because its extensions are not built. Try: gem pristine gem-wrappers-1.2.5 Ignoring gem-wrappers-1.2.4 because its extensions are not built. Try: gem pristine gem-wrappers-1.2.4 Ignoring pg-0.17.1 because its extensions are not built. Try: gem pristine pg-0.17.1 Ignoring psych-2.0.6 because its extensions are not built. Try: gem pristine psych-2.0.6 Ignoring sqlite3-1.3.9 because its extensions are not built. Try: gem pristine sqlite3-1.3.9 And while it's a simple fix, it keeps happening. Has anyone come across this before? $ ruby -v ruby 1.9.3p484 (2013-11-22 revision 43786) [x86_64-darwin11.2.0]