diff --git a/src/config/opttypes.c b/src/config/opttypes.c
index e79e42f0..ea308041 100644
--- a/src/config/opttypes.c
+++ b/src/config/opttypes.c
@@ -225,6 +225,11 @@ num_rd(struct option *opt, unsigned char **file, int *line)
 static int
 num_set(struct option *opt, unsigned char *str)
 {
+	/* In num_rd(), num_set(), and num_eq(), str always points
+	 * to a long, even though these functions are only used for
+	 * OPT_BOOL and OPT_INT, which use int option_value.number.
+	 * redir_rd(), redir_set(), and redir_eq() expect this.
+	 * So does l_set_option() in the Lua scripting backend.  */
 	opt->value.number = *((long *) str);
 	return 1;
 }
diff --git a/src/scripting/lua/core.c b/src/scripting/lua/core.c
index 8aec3a91..bff037bd 100644
--- a/src/scripting/lua/core.c
+++ b/src/scripting/lua/core.c
@@ -517,21 +517,21 @@ l_set_option(LS)
 	switch (opt->type) {
 	case OPT_BOOL:
 	{
-		int value;
+		/* option_types[OPT_BOOL].set expects a long even though it
+		 * saves the value to opt->value.number, which is an int.  */
+		long value = lua_toboolean(S, 2);
 
-		value = lua_toboolean(S, 2);
 		option_types[opt->type].set(opt, (unsigned char *) (&value));
 		break;
 	}
 	case OPT_INT:
-	{
-		int value = lua_tonumber(S, 2);
-		option_types[opt->type].set(opt, (unsigned char *) (&value));
-		break;
-	}
 	case OPT_LONG:
 	{
+		/* option_types[OPT_INT].set expects a long even though it
+		 * saves the value to opt->value.number, which is an int.
+		 * option_types[OPT_LONG].set of course wants a long too.  */
 		long value = lua_tonumber(S, 2);
+
 		option_types[opt->type].set(opt, (unsigned char *) (&value));
 		break;
 	}