Index: apertium/apertium-prelatex.l
--- apertium/apertium-prelatex.l.orig
+++ apertium/apertium-prelatex.l
@@ -11,6 +11,7 @@
 #include <vector>
 #include <apertium/latex_accentsmap.h>
 #include <apertium/string_utils.h>
+#include <unistd.h>
 
 extern "C" {
 #if !defined(__STDC__)
@@ -428,6 +429,12 @@ void usage(string const &progname)
 
 int main(int argc, char *argv[])
 {
+  if (pledge("stdio rpath wpath cpath", NULL) == -1)
+  {
+    wcerr << "pledge" << endl;
+    exit(EXIT_FAILURE);
+  }
+
   LtLocale::tryToSetLocale();
   size_t base = 0;