diff --git a/apps/flipcash/shared/blob/src/androidHostTest/kotlin/com/flipcash/app/blob/AndroidUploadImageCacheTest.kt b/apps/flipcash/shared/blob/src/androidHostTest/kotlin/com/flipcash/app/blob/AndroidUploadImageCacheTest.kt
new file mode 100644
index 0000000000..8b9dddde78
--- /dev/null
+++ b/apps/flipcash/shared/blob/src/androidHostTest/kotlin/com/flipcash/app/blob/AndroidUploadImageCacheTest.kt
@@ -0,0 +1,45 @@
+package com.flipcash.app.blob
+
+import android.content.Context
+import android.webkit.MimeTypeMap
+import androidx.test.core.app.ApplicationProvider
+import com.getcode.util.resources.AndroidContentReader
+import org.junit.Before
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.Shadows.shadowOf
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+/** The real cache, so a member that shadows the top-level `uploadMimeFor` recurses here instead of in production. */
+@RunWith(RobolectricTestRunner::class)
+class AndroidUploadImageCacheTest {
+
+    private val context: Context = ApplicationProvider.getApplicationContext()
+    private val cache = AndroidUploadImageCache(context, AndroidContentReader(context))
+
+    @Before
+    fun registerMimeTypes() {
+        shadowOf(MimeTypeMap.getSingleton()).apply {
+            addExtensionMimeTypeMapping("jpeg", "image/jpeg")
+            addExtensionMimeTypeMapping("jpg", "image/jpeg")
+            addExtensionMimeTypeMapping("png", "image/png")
+            addExtensionMimeTypeMapping("heic", "image/heic")
+        }
+    }
+
+    @Test
+    fun `a JPEG source uploads as JPEG`() {
+        assertEquals("image/jpeg", cache.uploadMimeFor("image/jpeg"))
+    }
+
+    @Test
+    fun `a non-JPEG source uploads as PNG`() {
+        assertEquals("image/png", cache.uploadMimeFor("image/heic"))
+    }
+
+    @Test
+    fun `an unknown source uploads as PNG`() {
+        assertEquals("image/png", cache.uploadMimeFor(null))
+    }
+}
diff --git a/apps/flipcash/shared/blob/src/androidMain/kotlin/com/flipcash/app/blob/AndroidUploadImageCache.kt b/apps/flipcash/shared/blob/src/androidMain/kotlin/com/flipcash/app/blob/AndroidUploadImageCache.kt
index ba925baf3f..fbbbe98681 100644
--- a/apps/flipcash/shared/blob/src/androidMain/kotlin/com/flipcash/app/blob/AndroidUploadImageCache.kt
+++ b/apps/flipcash/shared/blob/src/androidMain/kotlin/com/flipcash/app/blob/AndroidUploadImageCache.kt
@@ -2,7 +2,7 @@ package com.flipcash.app.blob
 
 import android.content.Context
 import com.getcode.util.resources.ContentReader
-import com.getcode.util.resources.uploadMimeFor
+import com.getcode.util.resources.uploadMimeFor as contentUploadMimeFor
 import dagger.hilt.android.qualifiers.ApplicationContext
 import javax.inject.Inject
 
@@ -13,7 +13,7 @@ internal class AndroidUploadImageCache @Inject constructor(
 ) : UploadImageCache {
     override fun mimeType(photo: PickedPhoto): String? = contentReader.mimeType(photo.toUri())
 
-    override fun uploadMimeFor(sourceMimeType: String?): String = uploadMimeFor(sourceMimeType)
+    override fun uploadMimeFor(sourceMimeType: String?): String = contentUploadMimeFor(sourceMimeType)
 
     override fun copyToCache(photo: PickedPhoto, fileName: String, maxSize: Int, mimeType: String?): PickedPhoto? =
         contentReader.copyToCache(photo.toUri(), fileName, maxSize, mimeType)