diff --git a/minui/Android.mk b/minui/Android.mk
index 4dfc65f..281f649 100644
--- a/minui/Android.mk
+++ b/minui/Android.mk
@@ -28,10 +28,7 @@
     libdrm \
     libsync_recovery
 
-LOCAL_STATIC_LIBRARIES := \
-    libpng \
-    libbase
-
+LOCAL_STATIC_LIBRARIES := libpng
 LOCAL_CFLAGS := -Werror
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
@@ -64,10 +61,7 @@
 include $(CLEAR_VARS)
 LOCAL_MODULE := libminui
 LOCAL_WHOLE_STATIC_LIBRARIES += libminui
-LOCAL_SHARED_LIBRARIES := \
-    libpng \
-    libbase
-
+LOCAL_SHARED_LIBRARIES := libpng
 LOCAL_CFLAGS := -Werror
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
diff --git a/minui/include/minui/minui.h b/minui/include/minui/minui.h
index 78dd4cb..a1749df 100644
--- a/minui/include/minui/minui.h
+++ b/minui/include/minui/minui.h
@@ -20,7 +20,6 @@
 #include <sys/types.h>
 
 #include <functional>
-#include <string>
 
 //
 // Graphics.
@@ -94,7 +93,7 @@
 // Resources
 //
 
-bool matches_locale(const std::string& prefix, const std::string& locale);
+bool matches_locale(const char* prefix, const char* locale);
 
 // res_create_*_surface() functions return 0 if no error, else
 // negative.
diff --git a/minui/resources.cpp b/minui/resources.cpp
index 86c731b..c0f9c5c 100644
--- a/minui/resources.cpp
+++ b/minui/resources.cpp
@@ -25,11 +25,8 @@
 #include <sys/types.h>
 #include <unistd.h>
 
-#include <regex>
-#include <string>
 #include <vector>
 
-#include <android-base/strings.h>
 #include <png.h>
 
 #include "minui/minui.h"
@@ -374,26 +371,16 @@
 
 // This function tests if a locale string stored in PNG (prefix) matches
 // the locale string provided by the system (locale).
-bool matches_locale(const std::string& prefix, const std::string& locale) {
-  // According to the BCP 47 format, A locale string may consists of:
-  // language-{extlang}-{script}-{region}-{variant}
-  // The locale headers in PNG mostly consist of language-{region} except for sr-Latn, and some
-  // android's system locale can have the format language-{script}-{region}.
+bool matches_locale(const char* prefix, const char* locale) {
+    if (locale == nullptr) {
+        return false;
+    }
 
-  // Return true if the whole string of prefix matches the top part of locale. Otherwise try to
-  // match the locale string without the {script} section.
-  // For instance, prefix == "en" matches locale == "en-US", prefix == "sr-Latn" matches locale
-  // == "sr-Latn-BA", and prefix == "zh-CN" matches locale == "zh-Hans-CN".
-  if (android::base::StartsWith(locale, prefix.c_str())) {
-    return true;
-  }
+    // Return true if the whole string of prefix matches the top part of
+    // locale. For instance, prefix == "en" matches locale == "en_US";
+    // and prefix == "zh_CN" matches locale == "zh_CN_#Hans".
 
-  size_t separator = prefix.find('-');
-  if (separator == std::string::npos) {
-    return false;
-  }
-  std::regex loc_regex(prefix.substr(0, separator) + "-[A-Za-z]*" + prefix.substr(separator));
-  return std::regex_match(locale, loc_regex);
+    return (strncmp(prefix, locale, strlen(prefix)) == 0);
 }
 
 int res_create_localized_alpha_surface(const char* name,
diff --git a/recovery.cpp b/recovery.cpp
index b24efa9..c226216 100644
--- a/recovery.cpp
+++ b/recovery.cpp
@@ -122,7 +122,7 @@
 static const int BATTERY_OK_PERCENTAGE = 20;
 static const int BATTERY_WITH_CHARGER_OK_PERCENTAGE = 15;
 static constexpr const char* RECOVERY_WIPE = "/etc/recovery.wipe";
-static constexpr const char* DEFAULT_LOCALE = "en-US";
+static constexpr const char* DEFAULT_LOCALE = "en_US";
 
 static std::string locale;
 static bool has_cache = false;
diff --git a/res-hdpi/images/erasing_text.png b/res-hdpi/images/erasing_text.png
index 0982544..684fc7c 100644
--- a/res-hdpi/images/erasing_text.png
+++ b/res-hdpi/images/erasing_text.png
Binary files differ
diff --git a/res-hdpi/images/error_text.png b/res-hdpi/images/error_text.png
index 3a06f6e..00c485d 100644
--- a/res-hdpi/images/error_text.png
+++ b/res-hdpi/images/error_text.png
Binary files differ
diff --git a/res-hdpi/images/installing_security_text.png b/res-hdpi/images/installing_security_text.png
index b1acd23..dadcfc3 100644
--- a/res-hdpi/images/installing_security_text.png
+++ b/res-hdpi/images/installing_security_text.png
Binary files differ
diff --git a/res-hdpi/images/installing_text.png b/res-hdpi/images/installing_text.png
index f0f5d8b..abe73b4 100644
--- a/res-hdpi/images/installing_text.png
+++ b/res-hdpi/images/installing_text.png
Binary files differ
diff --git a/res-hdpi/images/no_command_text.png b/res-hdpi/images/no_command_text.png
index def5036..958e106 100644
--- a/res-hdpi/images/no_command_text.png
+++ b/res-hdpi/images/no_command_text.png
Binary files differ
diff --git a/res-mdpi/images/erasing_text.png b/res-mdpi/images/erasing_text.png
index 82b4461..10e3178 100644
--- a/res-mdpi/images/erasing_text.png
+++ b/res-mdpi/images/erasing_text.png
Binary files differ
diff --git a/res-mdpi/images/error_text.png b/res-mdpi/images/error_text.png
index adb4513..0022d10 100644
--- a/res-mdpi/images/error_text.png
+++ b/res-mdpi/images/error_text.png
Binary files differ
diff --git a/res-mdpi/images/installing_security_text.png b/res-mdpi/images/installing_security_text.png
index 54e5564..7a4cd41 100644
--- a/res-mdpi/images/installing_security_text.png
+++ b/res-mdpi/images/installing_security_text.png
Binary files differ
diff --git a/res-mdpi/images/installing_text.png b/res-mdpi/images/installing_text.png
index d423318..ee95e56 100644
--- a/res-mdpi/images/installing_text.png
+++ b/res-mdpi/images/installing_text.png
Binary files differ
diff --git a/res-mdpi/images/no_command_text.png b/res-mdpi/images/no_command_text.png
index cd77ff4..af76609 100644
--- a/res-mdpi/images/no_command_text.png
+++ b/res-mdpi/images/no_command_text.png
Binary files differ
diff --git a/res-xhdpi/images/erasing_text.png b/res-xhdpi/images/erasing_text.png
index 333edbe..91cc358 100644
--- a/res-xhdpi/images/erasing_text.png
+++ b/res-xhdpi/images/erasing_text.png
Binary files differ
diff --git a/res-xhdpi/images/error_text.png b/res-xhdpi/images/error_text.png
index e262584..772b139 100644
--- a/res-xhdpi/images/error_text.png
+++ b/res-xhdpi/images/error_text.png
Binary files differ
diff --git a/res-xhdpi/images/installing_security_text.png b/res-xhdpi/images/installing_security_text.png
index e0f0f3e..a7113a0 100644
--- a/res-xhdpi/images/installing_security_text.png
+++ b/res-xhdpi/images/installing_security_text.png
Binary files differ
diff --git a/res-xhdpi/images/installing_text.png b/res-xhdpi/images/installing_text.png
index a7e67f5..566eb06 100644
--- a/res-xhdpi/images/installing_text.png
+++ b/res-xhdpi/images/installing_text.png
Binary files differ
diff --git a/res-xhdpi/images/no_command_text.png b/res-xhdpi/images/no_command_text.png
index 13aef7b..b8da125 100644
--- a/res-xhdpi/images/no_command_text.png
+++ b/res-xhdpi/images/no_command_text.png
Binary files differ
diff --git a/res-xxhdpi/images/erasing_text.png b/res-xxhdpi/images/erasing_text.png
index 80e7c47..86693f4 100644
--- a/res-xxhdpi/images/erasing_text.png
+++ b/res-xxhdpi/images/erasing_text.png
Binary files differ
diff --git a/res-xxhdpi/images/error_text.png b/res-xxhdpi/images/error_text.png
index 32a1965..9c4bcab 100644
--- a/res-xxhdpi/images/error_text.png
+++ b/res-xxhdpi/images/error_text.png
Binary files differ
diff --git a/res-xxhdpi/images/installing_security_text.png b/res-xxhdpi/images/installing_security_text.png
index c53c9ac..f5ec698 100644
--- a/res-xxhdpi/images/installing_security_text.png
+++ b/res-xxhdpi/images/installing_security_text.png
Binary files differ
diff --git a/res-xxhdpi/images/installing_text.png b/res-xxhdpi/images/installing_text.png
index 38b18d2..100a5b3 100644
--- a/res-xxhdpi/images/installing_text.png
+++ b/res-xxhdpi/images/installing_text.png
Binary files differ
diff --git a/res-xxhdpi/images/no_command_text.png b/res-xxhdpi/images/no_command_text.png
index a0666d8..590030c 100644
--- a/res-xxhdpi/images/no_command_text.png
+++ b/res-xxhdpi/images/no_command_text.png
Binary files differ
diff --git a/res-xxxhdpi/images/erasing_text.png b/res-xxxhdpi/images/erasing_text.png
index 4f7b37b..4cf5d76 100644
--- a/res-xxxhdpi/images/erasing_text.png
+++ b/res-xxxhdpi/images/erasing_text.png
Binary files differ
diff --git a/res-xxxhdpi/images/error_text.png b/res-xxxhdpi/images/error_text.png
index 052bf21..8dd6f12 100644
--- a/res-xxxhdpi/images/error_text.png
+++ b/res-xxxhdpi/images/error_text.png
Binary files differ
diff --git a/res-xxxhdpi/images/installing_security_text.png b/res-xxxhdpi/images/installing_security_text.png
index a9e739b..fa06f31 100644
--- a/res-xxxhdpi/images/installing_security_text.png
+++ b/res-xxxhdpi/images/installing_security_text.png
Binary files differ
diff --git a/res-xxxhdpi/images/installing_text.png b/res-xxxhdpi/images/installing_text.png
index 2d19486..d0f9301 100644
--- a/res-xxxhdpi/images/installing_text.png
+++ b/res-xxxhdpi/images/installing_text.png
Binary files differ
diff --git a/res-xxxhdpi/images/no_command_text.png b/res-xxxhdpi/images/no_command_text.png
index ee0c238..233aec4 100644
--- a/res-xxxhdpi/images/no_command_text.png
+++ b/res-xxxhdpi/images/no_command_text.png
Binary files differ
diff --git a/tests/unit/locale_test.cpp b/tests/unit/locale_test.cpp
index cdaba0e..f732350 100644
--- a/tests/unit/locale_test.cpp
+++ b/tests/unit/locale_test.cpp
@@ -19,15 +19,14 @@
 #include "minui/minui.h"
 
 TEST(LocaleTest, Misc) {
-  EXPECT_TRUE(matches_locale("zh-CN", "zh-Hans-CN"));
-  EXPECT_TRUE(matches_locale("zh", "zh-Hans-CN"));
-  EXPECT_FALSE(matches_locale("zh-HK", "zh-Hans-CN"));
-  EXPECT_TRUE(matches_locale("en-GB", "en-GB"));
-  EXPECT_TRUE(matches_locale("en", "en-GB"));
-  EXPECT_FALSE(matches_locale("en-GB", "en"));
-  EXPECT_FALSE(matches_locale("en-GB", "en-US"));
-  EXPECT_FALSE(matches_locale("en-US", ""));
-  // Empty locale prefix in the PNG file will match the input locale.
-  EXPECT_TRUE(matches_locale("", "en-US"));
-  EXPECT_TRUE(matches_locale("sr-Latn", "sr-Latn-BA"));
+    EXPECT_TRUE(matches_locale("zh_CN", "zh_CN_#Hans"));
+    EXPECT_TRUE(matches_locale("zh", "zh_CN_#Hans"));
+    EXPECT_FALSE(matches_locale("zh_HK", "zh_CN_#Hans"));
+    EXPECT_TRUE(matches_locale("en_GB", "en_GB"));
+    EXPECT_TRUE(matches_locale("en", "en_GB"));
+    EXPECT_FALSE(matches_locale("en_GB", "en"));
+    EXPECT_FALSE(matches_locale("en_GB", "en_US"));
+    EXPECT_FALSE(matches_locale("en_US", ""));
+    // Empty locale prefix in the PNG file will match the input locale.
+    EXPECT_TRUE(matches_locale("", "en_US"));
 }