diff --git a/app/src/main/java/de/westnordost/streetcomplete/data/elementfilter/StringWithCursor.kt b/app/src/main/java/de/westnordost/streetcomplete/data/elementfilter/StringWithCursor.kt
index d4e5451c7c..7002de15c1 100644
--- a/app/src/main/java/de/westnordost/streetcomplete/data/elementfilter/StringWithCursor.kt
+++ b/app/src/main/java/de/westnordost/streetcomplete/data/elementfilter/StringWithCursor.kt
@@ -24,9 +24,9 @@ class StringWithCursor(private val string: String) {
         return true
     }
 
-    /** Advances the cursor if str or str.toUpperCase() is the next thing at the cursor
+    /** Advances the cursor if str or str.uppercase() is the next thing at the cursor
      *
-     *  Returns whether the next string was the str or str.toUpperCase
+     *  Returns whether the next string was the str or str.uppercase
      */
     fun nextIsAndAdvanceIgnoreCase(str: String): Boolean {
         if (!nextIsIgnoreCase(str)) return false
@@ -72,7 +72,7 @@ class StringWithCursor(private val string: String) {
     fun nextIs(c: Char): Boolean = c == char
     fun nextIs(str: String): Boolean = string.startsWith(str, cursorPos)
     fun nextIsIgnoreCase(str: String): Boolean =
-        nextIs(str.toLowerCase()) || nextIs(str.toUpperCase())
+        nextIs(str.lowercase()) || nextIs(str.uppercase())
 
     fun nextMatches(regex: Regex): MatchResult? {
         val match = regex.find(string, cursorPos) ?: return null
diff --git a/app/src/main/java/de/westnordost/streetcomplete/data/quest/QuestController.kt b/app/src/main/java/de/westnordost/streetcomplete/data/quest/QuestController.kt
index cf4f1907ba..e084bba59a 100644
--- a/app/src/main/java/de/westnordost/streetcomplete/data/quest/QuestController.kt
+++ b/app/src/main/java/de/westnordost/streetcomplete/data/quest/QuestController.kt
@@ -19,7 +19,6 @@ import de.westnordost.streetcomplete.data.osmnotes.notequests.OsmNoteQuestContro
 import de.westnordost.streetcomplete.quests.note_discussion.NoteAnswer
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
-import java.util.Locale
 import javax.inject.Inject
 import javax.inject.Singleton
 import kotlin.collections.ArrayList
@@ -47,7 +46,7 @@ import kotlin.collections.ArrayList
 
         var fullText = "Unable to answer \"$questTitle\""
         if (q is OsmQuest && q.elementId > 0) {
-            val lowercaseTypeName = q.elementType.name.toLowerCase(Locale.US)
+            val lowercaseTypeName = q.elementType.name.lowercase()
             val elementId = q.elementId
             fullText += " for https://osm.org/$lowercaseTypeName/$elementId"
         }
diff --git a/app/src/main/java/de/westnordost/streetcomplete/map/tangram/KtMapController.kt b/app/src/main/java/de/westnordost/streetcomplete/map/tangram/KtMapController.kt
index b52f45da30..b653a1ddf7 100644
--- a/app/src/main/java/de/westnordost/streetcomplete/map/tangram/KtMapController.kt
+++ b/app/src/main/java/de/westnordost/streetcomplete/map/tangram/KtMapController.kt
@@ -359,7 +359,7 @@ class KtMapController(private val c: MapController, contentResolver: ContentReso
 class LoadSceneException(message: String, val sceneUpdate: SceneUpdate) : RuntimeException(message)
 
 private fun SceneError.toException() =
-    LoadSceneException(error.name.toLowerCase(Locale.US).replace("_", " "), sceneUpdate)
+    LoadSceneException(error.name.lowercase().replace("_", " "), sceneUpdate)
 
 
 suspend fun MapView.initMap(
diff --git a/app/src/main/java/de/westnordost/streetcomplete/user/CircularFlagView.kt b/app/src/main/java/de/westnordost/streetcomplete/user/CircularFlagView.kt
index d8b46e8590..2e3305bd50 100644
--- a/app/src/main/java/de/westnordost/streetcomplete/user/CircularFlagView.kt
+++ b/app/src/main/java/de/westnordost/streetcomplete/user/CircularFlagView.kt
@@ -10,7 +10,6 @@ import android.view.View
 import android.view.ViewOutlineProvider
 import de.westnordost.streetcomplete.R
 import de.westnordost.streetcomplete.ktx.getYamlObject
-import java.util.Locale
 import kotlin.math.min
 
 /** Show a flag of a country in a circle */
@@ -131,7 +130,7 @@ class CircularFlagView @JvmOverloads constructor(
     }
 
     private fun getFlagResId(countryCode: String): Int {
-        val lowerCaseCountryCode = countryCode.toLowerCase(Locale.US).replace('-', '_')
+        val lowerCaseCountryCode = countryCode.lowercase().replace('-', '_')
         return resources.getIdentifier("ic_flag_$lowerCaseCountryCode", "drawable", context.packageName)
     }
 
@@ -152,7 +151,7 @@ class CircularFlagView @JvmOverloads constructor(
 
         private fun readFlagAlignments(resources: Resources): Map<String, FlagAlignment> =
             resources.getYamlObject<HashMap<String, String>>(R.raw.flag_alignments).map {
-                it.key to FlagAlignment.valueOf(it.value.replace("-","_").toUpperCase(Locale.US))
+                it.key to FlagAlignment.valueOf(it.value.replace("-","_").uppercase())
             }.toMap()
     }
 
diff --git a/app/src/main/java/de/westnordost/streetcomplete/user/CountryInfoFragment.kt b/app/src/main/java/de/westnordost/streetcomplete/user/CountryInfoFragment.kt
index 3ef5861ff6..a33bf35cec 100644
--- a/app/src/main/java/de/westnordost/streetcomplete/user/CountryInfoFragment.kt
+++ b/app/src/main/java/de/westnordost/streetcomplete/user/CountryInfoFragment.kt
@@ -116,7 +116,7 @@ class CountryInfoFragment : AbstractInfoFakeDialogFragment(R.layout.fragment_cou
     }
 
     private fun getFlagResId(countryCode: String): Int {
-        val lowerCaseCountryCode = countryCode.toLowerCase(Locale.US).replace('-', '_')
+        val lowerCaseCountryCode = countryCode.lowercase().replace('-', '_')
         return resources.getIdentifier("ic_flag_$lowerCaseCountryCode", "drawable", requireContext().packageName)
     }
 
diff --git a/app/src/main/java/de/westnordost/streetcomplete/view/AutoCorrectAbbreviationsEditText.kt b/app/src/main/java/de/westnordost/streetcomplete/view/AutoCorrectAbbreviationsEditText.kt
index a54052a6c1..46d9c6bb6e 100644
--- a/app/src/main/java/de/westnordost/streetcomplete/view/AutoCorrectAbbreviationsEditText.kt
+++ b/app/src/main/java/de/westnordost/streetcomplete/view/AutoCorrectAbbreviationsEditText.kt
@@ -57,7 +57,7 @@ class AutoCorrectAbbreviationsEditText @JvmOverloads constructor(
             fixedReplace(s, wordStart, wordStart + lastWordBeforeCursor.length, replacement)
         } else if (lastWordBeforeCursor.length > 3) {
             val locale = abbrs.locale
-            val capital = lastWordBeforeCursor.substring(0, 1).toUpperCase(locale)
+            val capital = lastWordBeforeCursor.substring(0, 1).uppercase(locale)
             s.replace(wordStart, wordStart + 1, capital)
         }
     }