diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index 0cbe6db7d..e3266ea0a 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -176,6 +176,9 @@ dependencies {
     androidTestImplementation("androidx.test.ext:junit:1.1.5")
     androidTestImplementation("androidx.test.espresso:espresso-core:3.5.1")
 
+    testImplementation("org.mockito:mockito-core:5.4.0")
+    testImplementation("org.mockito.kotlin:mockito-kotlin:5.0.0")
+
     implementation("androidx.browser:browser:1.5.0")
 
     implementation("androidx.profileinstaller:profileinstaller:1.3.1")
diff --git a/app/src/main/java/com/jerboa/Utils.kt b/app/src/main/java/com/jerboa/Utils.kt
index 03a70e8cf..952c9fb46 100644
--- a/app/src/main/java/com/jerboa/Utils.kt
+++ b/app/src/main/java/com/jerboa/Utils.kt
@@ -691,42 +691,44 @@ data class InputField(
 )
 
 fun validatePostName(
+    ctx: Context,
     name: String,
 ): InputField {
     return if (name.isEmpty()) {
         InputField(
-            label = "Title required",
+            label = ctx.getString(R.string.title_required),
             hasError = true,
         )
     } else if (name.length < 3) {
         InputField(
-            label = "Title must be > 3 chars",
+            label = ctx.getString(R.string.title_min_3_chars),
             hasError = true,
         )
     } else if (name.length >= MAX_POST_TITLE_LENGTH) {
         InputField(
-            label = "Title cannot be > 200 chars",
+            label = ctx.getString(R.string.title_less_than_200_chars),
             hasError = true,
         )
     } else {
         InputField(
-            label = "Title",
+            label = ctx.getString(R.string.title),
             hasError = false,
         )
     }
 }
 
 fun validateUrl(
+    ctx: Context,
     url: String,
 ): InputField {
     return if (url.isNotEmpty() && !PatternsCompat.WEB_URL.matcher(url).matches()) {
         InputField(
-            label = "Invalid Url",
+            label = ctx.getString(R.string.url_invalid),
             hasError = true,
         )
     } else {
         InputField(
-            label = "Url",
+            label = ctx.getString(R.string.url),
             hasError = false,
         )
     }
diff --git a/app/src/main/java/com/jerboa/ui/components/post/create/CreatePostActivity.kt b/app/src/main/java/com/jerboa/ui/components/post/create/CreatePostActivity.kt
index 5b44468e5..ab5f5d839 100644
--- a/app/src/main/java/com/jerboa/ui/components/post/create/CreatePostActivity.kt
+++ b/app/src/main/java/com/jerboa/ui/components/post/create/CreatePostActivity.kt
@@ -84,8 +84,8 @@ fun CreatePostActivity(
     }
     var isUploadingImage by rememberSaveable { mutableStateOf(false) }
 
-    val nameField = validatePostName(name)
-    val urlField = validateUrl(url)
+    val nameField = validatePostName(ctx, name)
+    val urlField = validateUrl(ctx, url)
     val formValid = !nameField.hasError && !urlField.hasError && (selectedCommunity !== null)
 
     LaunchedEffect(initialUrl) {
diff --git a/app/src/main/java/com/jerboa/ui/components/post/edit/PostEditActivity.kt b/app/src/main/java/com/jerboa/ui/components/post/edit/PostEditActivity.kt
index 7e82f5cb3..0f9506546 100644
--- a/app/src/main/java/com/jerboa/ui/components/post/edit/PostEditActivity.kt
+++ b/app/src/main/java/com/jerboa/ui/components/post/edit/PostEditActivity.kt
@@ -68,8 +68,8 @@ fun PostEditActivity(
     }
     var isUploadingImage by rememberSaveable { mutableStateOf(false) }
 
-    val nameField = validatePostName(name)
-    val urlField = validateUrl(url)
+    val nameField = validatePostName(ctx, name)
+    val urlField = validateUrl(ctx, url)
     val formValid = !nameField.hasError && !urlField.hasError
 
     Scaffold(
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index abab2ff5b..b7919a857 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -303,7 +303,13 @@
     <string name="sorttype_topweek">TopWeek</string>
     <string name="sorttype_topyear">TopYear</string>
     <string name="time_ago_ago">%1$s %2$s ago</string>
+    <string name="title">Title</string>
+    <string name="title_less_than_200_chars">Title cannot be more than 200 characters</string>
+    <string name="title_min_3_chars">Title must be at least three characters</string>
+    <string name="title_required">Title required</string>
     <string name="topAppBar_back">Back</string>
+    <string name="url">URL</string>
+    <string name="url_invalid">Invalid URL</string>
     <string name="utils_login_first">Login first</string>
     <string name="upvote">Upvote</string>
     <string name="downvote">Downvote</string>
diff --git a/app/src/test/java/com/jerboa/UtilsKtTest.kt b/app/src/test/java/com/jerboa/UtilsKtTest.kt
index e4d7304cc..34a4ffb33 100644
--- a/app/src/test/java/com/jerboa/UtilsKtTest.kt
+++ b/app/src/test/java/com/jerboa/UtilsKtTest.kt
@@ -1,12 +1,20 @@
 package com.jerboa
 
+import android.content.Context
 import androidx.compose.ui.unit.dp
 import com.jerboa.api.API
 import com.jerboa.ui.theme.SMALL_PADDING
 import junitparams.JUnitParamsRunner
+import junitparams.Parameters
 import org.junit.Assert.*
+import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
+import org.mockito.ArgumentMatchers.anyInt
+import org.mockito.junit.MockitoJUnit
+import org.mockito.junit.MockitoRule
+import org.mockito.kotlin.doReturn
+import org.mockito.kotlin.mock
 import org.ocpsoft.prettytime.PrettyTime
 import java.time.Duration
 import java.time.Instant
@@ -15,6 +23,11 @@ import java.util.Locale
 
 @RunWith(JUnitParamsRunner::class)
 class UtilsKtTest {
+
+    @JvmField
+    @Rule
+    val rule: MockitoRule = MockitoJUnit.rule()
+
     @Test
     fun testCalculateCommentOffset() {
         assertEquals(0.dp, calculateCommentOffset(0, 0))
@@ -83,20 +96,31 @@ class UtilsKtTest {
 
     @Test
     fun testValidatePostName() {
-        assertTrue(validatePostName("").hasError)
-        assertTrue(validatePostName("a").hasError)
-        assertTrue(validatePostName("a".repeat(MAX_POST_TITLE_LENGTH)).hasError)
+        val ctx = mock<Context> {
+            on { getString(anyInt()) } doReturn ""
+        }
+
+        assertTrue(validatePostName(ctx, "").hasError)
+        assertTrue(validatePostName(ctx, "a").hasError)
+        assertTrue(validatePostName(ctx, "a".repeat(MAX_POST_TITLE_LENGTH)).hasError)
 
-        assertFalse(validatePostName("totally fine").hasError)
-        assertFalse(validatePostName("a".repeat(MAX_POST_TITLE_LENGTH - 1)).hasError)
+        assertFalse(validatePostName(ctx, "totally fine").hasError)
+        assertFalse(validatePostName(ctx, "a".repeat(MAX_POST_TITLE_LENGTH - 1)).hasError)
     }
 
     @Test
     fun testValidateUrl() {
-        assertTrue(validateUrl("nonsense").hasError)
+        val ctx = mock<Context> {
+            on { getString(R.string.url) } doReturn "url"
+            on { getString(R.string.url_invalid) } doReturn "url_invalid"
+        }
+
+        assertTrue(validateUrl(ctx, "nonsense").hasError)
+        assertSame("url_invalid", validateUrl(ctx, "nonsense").label)
 
-        assertFalse(validateUrl("").hasError)
-        assertFalse(validateUrl("https://example.com").hasError)
+        assertFalse(validateUrl(ctx, "").hasError)
+        assertFalse(validateUrl(ctx, "https://example.com").hasError)
+        assertSame("url", validateUrl(ctx, "https://example.com").label)
     }
 
     @Test
@@ -154,15 +178,20 @@ class UtilsKtTest {
     }
 
     @Test
-    fun testSiFormat() {
-        assertEquals("0", siFormat(0))
-        assertEquals("1K", siFormat(1000))
-        assertEquals("1.1K", siFormat(1100))
-        assertEquals("1M", siFormat(1000000))
-        assertEquals("1.2M", siFormat(1234500))
-        assertEquals("12M", siFormat(12345000))
+    @Parameters(method = "siFormatCases")
+    fun testSiFormat(expected: String, input: Int) {
+        assertEquals(expected, siFormat(input))
     }
 
+    fun siFormatCases() = listOf(
+        listOf("0", 0),
+        listOf("1K", 1000),
+        listOf("1.1K", 1100),
+        listOf("1M", 1000000),
+        listOf("1.2M", 1234500),
+        listOf("12M", 12345000),
+    )
+
     @Test
     fun testParseUrl() {
         val cases = mapOf(