diff --git a/engine/src/flutter/tests/FontCollectionItemizeTest.cpp b/engine/src/flutter/tests/FontCollectionItemizeTest.cpp
index cf9b704efa..57409a5e62 100644
--- a/engine/src/flutter/tests/FontCollectionItemizeTest.cpp
+++ b/engine/src/flutter/tests/FontCollectionItemizeTest.cpp
@@ -20,12 +20,15 @@
 #include "FontTestUtils.h"
 #include "ICUTestBase.h"
 #include "MinikinFontForTest.h"
+#include "MinikinInternal.h"
 #include "UnicodeUtils.h"
 
+using android::AutoMutex;
 using android::FontCollection;
 using android::FontFamily;
 using android::FontLanguage;
 using android::FontStyle;
+using android::gMinikinLock;
 
 const char kItemizeFontXml[] = kTestFontDir "itemize.xml";
 const char kEmojiFont[] = kTestFontDir "Emoji.ttf";
@@ -55,6 +58,7 @@ void itemize(FontCollection* collection, const char* str, FontStyle style,
 
     result->clear();
     ParseUnicode(buf, BUF_SIZE, str, &len, NULL);
+    AutoMutex _l(gMinikinLock);
     collection->itemize(buf, len, style, result);
 }
 
diff --git a/engine/src/flutter/tests/FontFamilyTest.cpp b/engine/src/flutter/tests/FontFamilyTest.cpp
index 5b4b28b316..6b32689081 100644
--- a/engine/src/flutter/tests/FontFamilyTest.cpp
+++ b/engine/src/flutter/tests/FontFamilyTest.cpp
@@ -31,11 +31,13 @@ typedef ICUTestBase FontLanguagesTest;
 typedef ICUTestBase FontLanguageTest;
 
 static FontLanguages createFontLanguages(const std::string& input) {
+    AutoMutex _l(gMinikinLock);
     uint32_t langId = FontLanguageListCache::getId(input);
     return FontLanguageListCache::getById(langId);
 }
 
 static FontLanguage createFontLanguage(const std::string& input) {
+    AutoMutex _l(gMinikinLock);
     uint32_t langId = FontLanguageListCache::getId(input);
     return FontLanguageListCache::getById(langId)[0];
 }
diff --git a/engine/src/flutter/tests/FontLanguageListCacheTest.cpp b/engine/src/flutter/tests/FontLanguageListCacheTest.cpp
index f83988c1f5..fbbd9376f0 100644
--- a/engine/src/flutter/tests/FontLanguageListCacheTest.cpp
+++ b/engine/src/flutter/tests/FontLanguageListCacheTest.cpp
@@ -20,17 +20,20 @@
 
 #include "FontLanguageListCache.h"
 #include "ICUTestBase.h"
+#include "MinikinInternal.h"
 
 namespace android {
 
 typedef ICUTestBase FontLanguageListCacheTest;
 
 TEST_F(FontLanguageListCacheTest, getId) {
-    EXPECT_EQ(0UL, FontLanguageListCache::getId(""));
     EXPECT_NE(0UL, FontStyle::registerLanguageList("en"));
     EXPECT_NE(0UL, FontStyle::registerLanguageList("jp"));
     EXPECT_NE(0UL, FontStyle::registerLanguageList("en,zh-Hans"));
 
+    AutoMutex _l(gMinikinLock);
+    EXPECT_EQ(0UL, FontLanguageListCache::getId(""));
+
     EXPECT_EQ(FontLanguageListCache::getId("en"), FontLanguageListCache::getId("en"));
     EXPECT_NE(FontLanguageListCache::getId("en"), FontLanguageListCache::getId("jp"));
 
@@ -47,6 +50,7 @@ TEST_F(FontLanguageListCacheTest, getId) {
 }
 
 TEST_F(FontLanguageListCacheTest, getById) {
+    AutoMutex _l(gMinikinLock);
     uint32_t enLangId = FontLanguageListCache::getId("en");
     uint32_t jpLangId = FontLanguageListCache::getId("jp");
     FontLanguage english = FontLanguageListCache::getById(enLangId)[0];