--- a/IlmBase.pc.in

+++ b/IlmBase.pc.in

@@ -15,3 +15,4 @@ Requires:

 Conflicts:

 Libs: -L${libdir} -lImath${libsuffix} -lHalf${libsuffix} -lIex${libsuffix} -lIexMath${libsuffix} -lIlmThread${libsuffix} @PTHREAD_LIBS@

 Cflags: @PTHREAD_CFLAGS@ -I${includedir} -I${includedir}/OpenEXR

+Requires.private: gl glu