diff --git a/src/Makevars.in b/src/Makevars.in
index fcfaceba9..8cf8db729 100644
--- a/src/Makevars.in
+++ b/src/Makevars.in
@@ -1,5 +1,5 @@
-PKG_CFLAGS = @PKG_CFLAGS@ @openmp_cflags@ @zlib_cflags@
-PKG_LIBS = @PKG_LIBS@ @openmp_cflags@ @zlib_libs@
+PKG_CFLAGS = $(C_VISIBILITY) @PKG_CFLAGS@ @openmp_cflags@ @zlib_cflags@
+PKG_LIBS = $(C_VISIBILITY) @PKG_LIBS@ @openmp_cflags@ @zlib_libs@
 # See WRE $1.2.1.1. But retain user supplied PKG_* too, #4664.
 # WRE states ($1.6) that += isn't portable and that we aren't allowed to use it.
 # Otherwise we could use the much simpler PKG_LIBS += @openmp_cflags@ -lz.
diff --git a/src/data.table-win.def b/src/data.table-win.def
new file mode 100644
index 000000000..db6418767
--- /dev/null
+++ b/src/data.table-win.def
@@ -0,0 +1,3 @@
+LIBRARY data.table.dll
+EXPORTS
+ R_init_data_table