diff --git a/src/battle.c b/src/battle.c
index 9761f2978..9608a382e 100644
--- a/src/battle.c
+++ b/src/battle.c
@@ -2297,7 +2297,6 @@ void do_attack(fighter * af)
         /* Wir suchen eine beliebige Feind-Einheit aus. An der können
          * wir feststellen, ob noch jemand da ist. */
         int apr, attacks = attacks_per_round(ta);
-        assert(attacks <= RACE_ATTACKS);
         if (!count_enemies(b, af, FIGHT_ROW, LAST_ROW, SELECT_FIND))
             break;
 
diff --git a/src/kernel/save.c b/src/kernel/save.c
index fdfe9aad9..928feedf2 100644
--- a/src/kernel/save.c
+++ b/src/kernel/save.c
@@ -1119,7 +1119,7 @@ void read_spellbook(spellbook **bookp, struct storage *store, int(*get_level)(co
                 *bookp = create_spellbook(0);
                 sb = *bookp;
             }
-            if (global.data_version >= SPELLBOOK_VERSION || !spellbook_get(sb, sp)) {
+            if (level>0 && (global.data_version >= SPELLBOOK_VERSION || !spellbook_get(sb, sp))) {
                 spellbook_add(sb, sp, level);
             }
         }
diff --git a/src/laws.c b/src/laws.c
index 40d224e7f..f85c8c063 100755
--- a/src/laws.c
+++ b/src/laws.c
@@ -3772,6 +3772,10 @@ int use_cmd(unit * u, struct order *ord)
     init_order(ord);
 
     t = gettoken(token, sizeof(token));
+    if (!t) {
+        cmistake(u, ord, 43, MSG_PRODUCE);
+        return err;
+    }
     n = atoi((const char *)t);
     if (n == 0) {
         if (isparam(t, u->faction->locale, P_ANY)) {
diff --git a/src/study.c b/src/study.c
index 90d838bfb..467939dbf 100644
--- a/src/study.c
+++ b/src/study.c
@@ -42,6 +42,7 @@ OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 #include <util/attrib.h>
 #include <util/base36.h>
 #include <util/language.h>
+#include <util/log.h>
 #include <util/parser.h>
 #include <util/rand.h>
 #include <util/umlaut.h>
@@ -217,8 +218,12 @@ bool report, int *academy)
         }
         if (index < MAXTEACHERS)
             teach->teachers[index++] = teacher;
-        if (index < MAXTEACHERS)
+        if (index < MAXTEACHERS) {
             teach->teachers[index] = NULL;
+        }
+        else {
+            log_warning("MAXTEACHERS is too low at %d", MAXTEACHERS);
+        }
         teach->value += n;
 
         /* Solange Akademien groessenbeschraenkt sind, sollte Lehrer und
diff --git a/src/study.h b/src/study.h
index dce5c0b34..88a6daa5b 100644
--- a/src/study.h
+++ b/src/study.h
@@ -32,7 +32,7 @@ extern "C" {
     extern bool is_migrant(struct unit *u);
     extern int study_cost(struct unit *u, skill_t talent);
 
-#define MAXTEACHERS 4
+#define MAXTEACHERS 8
     typedef struct teaching_info {
         struct unit *teachers[MAXTEACHERS];
         int value;