diff --git a/src/libs/utils/fileutils.cpp b/src/libs/utils/fileutils.cpp
index 91d692a1a70..6c399810857 100644
--- a/src/libs/utils/fileutils.cpp
+++ b/src/libs/utils/fileutils.cpp
@@ -994,3 +994,11 @@ void withNtfsPermissions(const std::function<void()> &task)
 }
 #endif
 } // namespace Utils
+
+std::hash<Utils::FilePath>::result_type
+    std::hash<Utils::FilePath>::operator()(const std::hash<Utils::FilePath>::argument_type &fn) const
+{
+    if (Utils::HostOsInfo::fileNameCaseSensitivity() == Qt::CaseInsensitive)
+        return hash<string>()(fn.toString().toUpper().toStdString());
+    return hash<string>()(fn.toString().toStdString());
+}
diff --git a/src/libs/utils/fileutils.h b/src/libs/utils/fileutils.h
index f1f13bbee1c..fa3e434ff0c 100644
--- a/src/libs/utils/fileutils.h
+++ b/src/libs/utils/fileutils.h
@@ -294,12 +294,7 @@ template<> struct hash<Utils::FilePath>
 {
     using argument_type = Utils::FilePath;
     using result_type = size_t;
-    result_type operator()(const argument_type &fn) const
-    {
-        if (Utils::HostOsInfo::fileNameCaseSensitivity() == Qt::CaseInsensitive)
-            return hash<string>()(fn.toString().toUpper().toStdString());
-        return hash<string>()(fn.toString().toStdString());
-    }
+    result_type operator()(const argument_type &fn) const;
 };
 } // namespace std