diff --git a/src/common/kernel/unit.c b/src/common/kernel/unit.c
index 1ae647be4..87f76a9e9 100644
--- a/src/common/kernel/unit.c
+++ b/src/common/kernel/unit.c
@@ -49,6 +49,7 @@
 #include <util/event.h>
 #include <util/goodies.h>
 #include <util/lists.h>
+#include <util/log.h>
 #include <util/resolve.h>
 #include <util/rng.h>
 #include <util/variant.h>
@@ -524,10 +525,11 @@ free_units(void)
 	}
 }
 
+
 void
 write_unit_reference(const unit * u, FILE * F)
 {
-  assert(u->number>0);
+  assert(u==NULL || u->number>0);
   fprintf(F, "%s ", (u!=NULL && u->no!=0)?itoa36(u->no):"0");
 }
 
@@ -1406,10 +1408,18 @@ countheroes(const struct faction * f)
 {
   const unit * u = f->units;
   int n = 0;
+  int m = 0;
+
   while (u) {
     if (fval(u, UFL_HERO)) n+= u->number;
     u = u->nextF;
   }
+#ifndef NDEBUG
+  m = maxheroes(f);
+  if (n>m) {
+    log_warning(("%s has %d of %d heroes\n", factionname(f), n, m));
+  }
+#endif
   return n;
 }
 
diff --git a/src/eressea/lua/faction.cpp b/src/eressea/lua/faction.cpp
index 300101226..b4191add5 100644
--- a/src/eressea/lua/faction.cpp
+++ b/src/eressea/lua/faction.cpp
@@ -277,15 +277,27 @@ faction_setorigin_x(faction& f, short x) {
   f.ursprung->x = x;
 }
 
-short
+static short
 faction_getorigin_y(const faction& f) {
   return f.ursprung->y;
 }
-void
+
+static void
 faction_setorigin_y(faction& f, short y) {
   f.ursprung->y = y;
 }
 
+static int
+faction_countheroes(const faction& f)
+{
+  return countheroes(&f);
+}
+
+static int
+faction_maxheroes(const faction& f)
+{
+  return maxheroes(&f);
+}
 
 void
 bind_faction(lua_State * L) 
@@ -301,9 +313,16 @@ bind_faction(lua_State * L)
     .def(self == faction())
     .def("set_policy", &faction_setpolicy)
     .def("get_policy", &faction_getpolicy)
+
+    // temporary variables
     .def("set_variable", &faction_set_variable)
     .def("get_variable", &faction_get_variable)
     .def("delete_variable", &faction_delete_variable)
+
+    // heroes
+    .def("heroes", &faction_countheroes)
+    .def("max_heroes", &faction_maxheroes)
+
     .def_readonly("name", &faction::name)
     .def_readonly("score", &faction::score)
     .def_readonly("id", &faction::no)