diff --git a/Source/GmmLib/igdgmm.pc.in b/Source/GmmLib/igdgmm.pc.in
index 9500c45..c54736e 100644
--- a/Source/GmmLib/igdgmm.pc.in
+++ b/Source/GmmLib/igdgmm.pc.in
@@ -6,5 +6,5 @@
 Name: igdgmm
 Description: Intel(R) Graphics Memory Management Library
 Version: @MAJOR_VERSION@.@MINOR_VERSION@.@PATCH_VERSION@
-Cflags: -I${includedir} -I${includedir}/GmmLib -I${includedir}/GmmLib/inc -I${includedir}/inc -I${includedir}/inc/common -I${includedir}/util
+Cflags: -DGMM_LIB_DLL -I${includedir} -I${includedir}/GmmLib -I${includedir}/GmmLib/inc -I${includedir}/inc -I${includedir}/inc/common -I${includedir}/util
 Libs: -L${libdir} -ligdgmm