diff --git a/src/plugins/coreplugin/documentmanager.cpp b/src/plugins/coreplugin/documentmanager.cpp
index 44ca515d717..7752c6a922a 100644
--- a/src/plugins/coreplugin/documentmanager.cpp
+++ b/src/plugins/coreplugin/documentmanager.cpp
@@ -149,7 +149,7 @@ public:
     QMap<FilePath, FileState> m_states; // filePathKey -> FileState
     QSet<FilePath> m_changedFiles; // watched file paths collected from file watcher notifications
     QList<IDocument *> m_documentsWithoutWatch;
-    QMap<IDocument *, FilePaths> m_documentsWithWatch; // document -> list of filePathKeys
+    QHash<IDocument *, FilePaths> m_documentsWithWatch; // document -> list of filePathKeys
     QSet<FilePath> m_expectedFileNames; // set of file paths without normalization
 
     QList<DocumentManager::RecentFile> m_recentFiles;
@@ -367,9 +367,10 @@ void DocumentManager::addDocuments(const QList<IDocument *> &documents, bool add
 static void removeFileInfo(IDocument *document)
 {
     QTC_ASSERT(isMainThread(), return);
-    if (!d->m_documentsWithWatch.contains(document))
+    const auto it = d->m_documentsWithWatch.constFind(document);
+    if (it == d->m_documentsWithWatch.constEnd())
         return;
-    const FilePaths filePaths = d->m_documentsWithWatch.value(document);
+    const FilePaths filePaths = *it;
     for (const FilePath &filePath : filePaths) {
         if (!d->m_states.contains(filePath))
             continue;
@@ -393,7 +394,7 @@ static void removeFileInfo(IDocument *document)
             d->m_states.remove(filePath);
         }
     }
-    d->m_documentsWithWatch.remove(document);
+    d->m_documentsWithWatch.erase(it);
 }
 
 /// Dumps the state of the file manager's map
@@ -448,9 +449,8 @@ void DocumentManager::renamedFile(const Utils::FilePath &from, const Utils::File
 
     // gather the list of IDocuments
     QList<IDocument *> documentsToRename;
-    for (auto it = d->m_documentsWithWatch.cbegin(), end = d->m_documentsWithWatch.cend();
-            it != end; ++it) {
-        if (it.value().contains(fromKey))
+    for (auto it = d->m_documentsWithWatch.cbegin(); it != d->m_documentsWithWatch.cend(); ++it) {
+        if (it->contains(fromKey))
             documentsToRename.append(it.key());
     }
 
@@ -544,9 +544,8 @@ QList<IDocument *> DocumentManager::modifiedDocuments()
 {
     QList<IDocument *> modified;
 
-    const auto docEnd = d->m_documentsWithWatch.keyEnd();
-    for (auto docIt = d->m_documentsWithWatch.keyBegin(); docIt != docEnd; ++docIt) {
-        IDocument *document = *docIt;
+    for (auto it = d->m_documentsWithWatch.cbegin(); it != d->m_documentsWithWatch.cend(); ++it) {
+        IDocument *document = it.key();
         if (document->isModified())
             modified << document;
     }