diff --git a/glu.pc.in b/glu.pc.in
index 939740d..8bb957a 100644
--- a/glu.pc.in
+++ b/glu.pc.in
@@ -9,3 +9,4 @@ Requires: @GLU_REQUIRES@
 Version: @VERSION@
 Libs: -L${libdir} -lGLU
 Libs.private: -lm
+Cflags: -I${includedir}