diff --git a/NEWS.md b/NEWS.md
index bc7b59e..374d5a0 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,7 @@
 # glue (development version)
 
+* Add `$(C_VISIBILITY)` to compiler flags to hide internal symbols from the dll (#284 @lionel-).
+
 # glue 1.6.2
 
 * Modify a test for better forward compatibility with R.
diff --git a/src/Makevars b/src/Makevars
new file mode 100644
index 0000000..bf5eb42
--- /dev/null
+++ b/src/Makevars
@@ -0,0 +1 @@
+PKG_CFLAGS = $(C_VISIBILITY)
diff --git a/src/init.c b/src/init.c
index c43e462..3f4c51f 100644
--- a/src/init.c
+++ b/src/init.c
@@ -3,6 +3,11 @@
 #include <Rinternals.h>
 #include <stdlib.h> // for NULL
 
+// Compile with `C_VISIBILITY = -fvisibility=hidden` if you link to
+// this library
+#include <R_ext/Visibility.h>
+#define export attribute_visible extern
+
 /* .Call calls */
 extern SEXP glue_(SEXP, SEXP, SEXP, SEXP, SEXP, SEXP);
 extern SEXP trim_(SEXP);
@@ -12,6 +17,7 @@ static const R_CallMethodDef CallEntries[] = {
     {"trim_", (DL_FUNC)&trim_, 1},
     {NULL, NULL, 0}};
 
+export
 void R_init_glue(DllInfo* dll) {
   R_registerRoutines(dll, NULL, CallEntries, NULL, NULL);
   R_useDynamicSymbols(dll, FALSE);