diff --git a/tests/lapi/debug_torture_test.lua b/tests/lapi/debug_torture_test.lua
index a9c59a9..1b0b864 100644
--- a/tests/lapi/debug_torture_test.lua
+++ b/tests/lapi/debug_torture_test.lua
@@ -171,7 +171,8 @@ local function TestOneInput(buf)
     local n_hook_mask = fdp:consume_integer(0, #hook_mask)
     local mask = {}
     for _ = 0, n_hook_mask do
-        table.insert(mask, fdp:oneof(hook_mask))
+        local m = fdp:oneof(hook_mask)
+        table.insert(mask, m)
     end
 
     -- Turn on the hook.
diff --git a/tests/lapi/os_time_test.lua b/tests/lapi/os_time_test.lua
index cc6e742..981ffed 100644
--- a/tests/lapi/os_time_test.lua
+++ b/tests/lapi/os_time_test.lua
@@ -32,7 +32,11 @@ local function TestOneInput(buf)
     local err_handler = test_lib.err_handler(ignored_msgs)
     local ok, res = xpcall(os.time, err_handler, time)
     if not ok then return end
-    assert(type(res) == "number" or type(res) == "table")
+    io.stderr:write(type(res) .. "\n")
+    assert(type(res) == "number" or
+           type(res) == "table" or
+           -- Undocumented.
+           res == nil)
 end
 
 local args = {
diff --git a/tests/lapi/string_pack_test.lua b/tests/lapi/string_pack_test.lua
index 3ea30af..37ab7aa 100644
--- a/tests/lapi/string_pack_test.lua
+++ b/tests/lapi/string_pack_test.lua
@@ -17,6 +17,10 @@ if not test_lib.lua_current_version_ge_than(5, 3) then
     os.exit(0)
 end
 
+local ignored_msgs = {
+    "invalid format option",
+}
+
 local function TestOneInput(buf, _size)
     local fdp = luzer.FuzzedDataProvider(buf)
     os.setlocale(test_lib.random_locale(fdp), "all")
@@ -26,7 +30,10 @@ local function TestOneInput(buf, _size)
     end
     local n = fdp:consume_integer(1, test_lib.MAX_INT)
     local values = fdp:consume_strings(test_lib.MAX_STR_LEN,  n)
-    string.pack(fmt_str, table.unpack(values))
+    local err_handler = test_lib.err_handler(ignored_msgs)
+    local ok, _ = xpcall(string.pack, err_handler, fmt_str,
+                         table.unpack(values))
+    if not ok then return end
 end
 
 local args = {
diff --git a/tests/lapi/utf8_offset_test.lua b/tests/lapi/utf8_offset_test.lua
index 79c6623..d87a370 100644
--- a/tests/lapi/utf8_offset_test.lua
+++ b/tests/lapi/utf8_offset_test.lua
@@ -19,6 +19,10 @@ if test_lib.lua_current_version_lt_than(5, 3) then
     os.exit()
 end
 
+local ignored_msgs = {
+    "initial position is a continuation byte",
+}
+
 local function TestOneInput(buf)
     local fdp = luzer.FuzzedDataProvider(buf)
     local max_len = fdp:consume_integer(0, MAX_INT)
@@ -26,7 +30,9 @@ local function TestOneInput(buf)
     local n = fdp:consume_integer(MIN_INT, MAX_INT)
     local i = fdp:consume_integer(1, MAX_INT)
     os.setlocale(test_lib.random_locale(fdp), "all")
-    utf8.offset(s, n, i)
+    local err_handler = test_lib.err_handler(ignored_msgs)
+    local ok, _ = xpcall(utf8.offset, err_handler, s, n, i)
+    if not ok then return end
 end
 
 local args = {