diff -ur cfitsio/cfitsio.pc.in cfitsio.new/cfitsio.pc.in
--- cfitsio/cfitsio.pc.in	2011-10-29 16:54:43.081132723 +0200
+++ cfitsio.new/cfitsio.pc.in	2011-10-29 16:56:49.933619756 +0200
@@ -8,4 +8,4 @@
 Version: 3.240
 Libs: -L${libdir} -lcfitsio @LIBS@
 Libs.private: -lm
-Cflags: -I${includedir}
+Cflags: -D_REENTRANT -I${includedir}