diff -ur a/cfitsio.pc.in b/cfitsio.pc.in
--- a/cfitsio.pc.in	2022-05-26 17:25:47.094287274 +0200
+++ b/cfitsio.pc.in	2022-05-26 17:30:27.552413663 +0200
@@ -1,12 +1,12 @@
 prefix=@prefix@
 exec_prefix=@exec_prefix@
 libdir=@libdir@
-includedir=@includedir@
+includedir=@includedir@/cfitsio
 
 Name: cfitsio
 Description: FITS File Subroutine Library
 URL: https://heasarc.gsfc.nasa.gov/fitsio/
 Version: @CFITSIO_MAJOR@.@CFITSIO_MINOR@.@CFITSIO_MICRO@
 Libs: -L${libdir} -lcfitsio
-Libs.private: -lm @LIBS@
-Cflags: -I${includedir}
+Libs.private: -lm -lz @LIBS@
+Cflags: -D_REENTRANT -I${includedir}