diff --git a/src/common/kernel/alchemy.c b/src/common/kernel/alchemy.c
index 960a03368..7df7d05a5 100644
--- a/src/common/kernel/alchemy.c
+++ b/src/common/kernel/alchemy.c
@@ -197,7 +197,7 @@ a_readeffect(attrib *a, FILE *f)
 		fscanf(f, "%s %d", zText, &power);
 		ptype = pt_find(zText);
 	}
-	if (ptype==NULL || power==0) return AT_READ_FAIL;
+	if (ptype==NULL || power<=0) return AT_READ_FAIL;
 	edata->type = ptype;
 	edata->value = power;
 	return AT_READ_OK;
diff --git a/src/common/kernel/build.c b/src/common/kernel/build.c
index 62073b534..1a0d62b73 100644
--- a/src/common/kernel/build.c
+++ b/src/common/kernel/build.c
@@ -546,8 +546,9 @@ build_road(region * r, unit * u, int size, direction_t d)
     int dm = get_effect(u, oldpotiontype[P_DOMORE]);
     if (dm != 0) {
       int sk = eff_skill(u, SK_ROAD_BUILDING, r);
-      dm = (left - n + sk - 1) / sk;
-      dm = min(dm, u->number);
+      int todo = (left - n + sk - 1) / sk;
+      todo = min(todo, u->number);
+      dm = min(dm, todo);
       change_effect(u, oldpotiontype[P_DOMORE], -dm);
       n += dm * sk;
     }             /* Auswirkung Schaffenstrunk */