diff --git a/fastmap/src/Makevars b/fastmap/src/Makevars
index bed55df..31d7752 100644
--- a/fastmap/src/Makevars
+++ b/fastmap/src/Makevars
@@ -1,4 +1,3 @@
 # Require Rf_ prefix for R's functions, to avoid clashes.
 PKG_CXXFLAGS=-DR_NO_REMAP
 
-PKG_CPPFLAGS=-Ilib/