diff --git a/CHANGELOG.md b/CHANGELOG.md
index 699e8bda..991542b6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## Unreleased
 
+### Fixed
+
+- Detection of duplicate titles in scanned files (#131)
+
 ### Changed
 
 - dependency updates:
diff --git a/cli/src/main/kotlin/com/github/zeldigas/text2confl/cli/ClicktExt.kt b/cli/src/main/kotlin/com/github/zeldigas/text2confl/cli/ClicktExt.kt
index bf1785a9..6b5b7f89 100644
--- a/cli/src/main/kotlin/com/github/zeldigas/text2confl/cli/ClicktExt.kt
+++ b/cli/src/main/kotlin/com/github/zeldigas/text2confl/cli/ClicktExt.kt
@@ -8,8 +8,8 @@ import com.github.ajalt.clikt.parameters.options.RawOption
 import com.github.ajalt.clikt.parameters.options.nullableFlag
 import com.github.ajalt.mordant.terminal.ConfirmationPrompt
 import com.github.ajalt.mordant.terminal.StringPrompt
+import com.github.zeldigas.text2confl.convert.ConversionException
 import com.github.zeldigas.text2confl.convert.ConversionFailedException
-import com.github.zeldigas.text2confl.convert.FileDoesNotExistException
 import com.github.zeldigas.text2confl.core.ContentValidationFailedException
 import com.github.zeldigas.text2confl.core.upload.ContentUploadException
 import com.github.zeldigas.text2confl.core.upload.InvalidTenantException
@@ -33,7 +33,7 @@ fun RawOption.optionalFlag(vararg secondaryNames: String): NullableOption<Boolea
 fun tryHandleException(ex: Exception): Nothing {
     when (ex) {
         is InvalidTenantException -> error(ex.message!!)
-        is FileDoesNotExistException -> error(ex.message!!)
+        is ConversionException -> error(ex.message!!)
         is ContentUploadException -> error(ex.message!!)
         is ConversionFailedException -> {
             val reason = buildString {
diff --git a/convert/src/main/kotlin/com/github/zeldigas/text2confl/convert/Converter.kt b/convert/src/main/kotlin/com/github/zeldigas/text2confl/convert/Converter.kt
index af46519b..60bde951 100644
--- a/convert/src/main/kotlin/com/github/zeldigas/text2confl/convert/Converter.kt
+++ b/convert/src/main/kotlin/com/github/zeldigas/text2confl/convert/Converter.kt
@@ -9,10 +9,7 @@ import com.github.zeldigas.text2confl.convert.markdown.MarkdownFileConverter
 import java.io.File
 import java.nio.file.Files
 import java.nio.file.Path
-import kotlin.io.path.exists
-import kotlin.io.path.extension
-import kotlin.io.path.listDirectoryEntries
-import kotlin.io.path.nameWithoutExtension
+import kotlin.io.path.*
 
 interface Converter {
 
@@ -22,7 +19,10 @@ interface Converter {
 
 }
 
-class FileDoesNotExistException(val file: Path) : RuntimeException("File does not exist: $file")
+open class ConversionException(message: String) : RuntimeException(message)
+
+class FileDoesNotExistException(val file: Path) : ConversionException("File does not exist: $file")
+class DuplicateTitlesException(val duplicates: List<String>, message: String) : ConversionException(message)
 
 const val DEFAULT_AUTOGEN_BANNER =
     "Edit <a href=\"__doc-root____file__\">source file</a> instead of changing page in Confluence. " +
@@ -77,12 +77,32 @@ internal class UniversalConverter(
     override fun convertDir(dir: Path): List<Page> {
         val documents = scanDocuments(dir)
 
+        checkForDuplicates(dir, documents)
+
         return convertFilesInDirectory(
             dir,
             ConvertingContext(ReferenceProvider.fromDocuments(dir, documents), conversionParameters, space)
         )
     }
 
+    private fun checkForDuplicates(base: Path, documents: Map<Path, PageHeader>) {
+        val duplicates = documents.entries
+            .groupBy { (_, v) -> v.title }
+            .entries.asSequence()
+            .filter { (_, v) -> v.size > 1 }
+            .map { (title, v) -> title to v.map { it.key.relativeTo(base) }.sorted() }
+            .map { (title, paths) -> "\"$title\": ${paths.joinToString(", ")}" }
+            .toList()
+        if (duplicates.isNotEmpty()) {
+            throw DuplicateTitlesException(
+                duplicates,
+                "Files with duplicate titles detected. Confluence has flat structure and every published page must have unique title.\n${
+                    duplicates.joinToString("\n")
+                }"
+            )
+        }
+    }
+
     private fun scanDocuments(dir: Path) =
         dir.toFile().walk().filter { it.supported() }
             .map {
diff --git a/convert/src/test/kotlin/com/github/zeldigas/text2confl/convert/UniversalConverterTest.kt b/convert/src/test/kotlin/com/github/zeldigas/text2confl/convert/UniversalConverterTest.kt
index 7456f9b2..9f23865c 100644
--- a/convert/src/test/kotlin/com/github/zeldigas/text2confl/convert/UniversalConverterTest.kt
+++ b/convert/src/test/kotlin/com/github/zeldigas/text2confl/convert/UniversalConverterTest.kt
@@ -17,8 +17,10 @@ import io.mockk.junit5.MockKExtension
 import io.mockk.mockkStatic
 import io.mockk.verify
 import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
 import org.junit.jupiter.api.extension.ExtendWith
 import org.junit.jupiter.api.io.TempDir
+import java.io.File
 import java.nio.file.Files
 import java.nio.file.Path
 import java.nio.file.Paths
@@ -84,6 +86,34 @@ internal class UniversalConverterTest(
 
     @Test
     internal fun `Directory conversion`(@TempDir dir: Path) {
+        createFileStructure(
+            dir,
+            "one.t",
+            "_two.t",
+            "three.t",
+            "three/foo.t",
+            "three/one.t",
+            "three/bar.md",
+            "four.md",
+            "five.adoc",
+            "another/hello.t",
+            "another/foo.t",
+        )
+        every { fileConverter.readHeader(any(), any()) } answers {
+            val file = it.invocation.args[0] as Path
+            PageHeader(file.fileName.toString(), emptyMap())
+        }
+        val exception = assertThrows<DuplicateTitlesException> { converter.convertDir(dir) }
+        assertThat(exception).all {
+            prop(DuplicateTitlesException::duplicates).hasSize(2)
+            messageContains("Files with duplicate titles detected. Confluence has flat structure and every published page must have unique title")
+            messageContains(""""one.t": one.t, three${File.separator}one.t""")
+            messageContains(""""foo.t": another${File.separator}foo.t, three${File.separator}foo.t""")
+        }
+    }
+
+    @Test
+    internal fun `Detection of documents with duplicate titles`(@TempDir dir: Path) {
         createFileStructure(
             dir,
             "one.t",