diff --git a/data/core/init.lua b/data/core/init.lua
index 95eb7973..992eb5de 100644
--- a/data/core/init.lua
+++ b/data/core/init.lua
@@ -194,6 +194,16 @@ local function project_scan_thread()
 end
 
 
+function core.is_project_folder(dirname)
+  for _, dir in ipairs(core.project_directories) do
+    if dir.name == dirname then
+      return true
+    end
+  end
+  return false
+end
+
+
 function core.scan_project_folder(dirname, filename)
   for _, dir in ipairs(core.project_directories) do
     if dir.name == dirname then
diff --git a/data/plugins/treeview.lua b/data/plugins/treeview.lua
index 8615343a..8214bda4 100644
--- a/data/plugins/treeview.lua
+++ b/data/plugins/treeview.lua
@@ -222,10 +222,19 @@ function TreeView:on_mouse_pressed(button, x, y, clicks)
     else
       if core.project_files_limit and not hovered_item.expanded then
         local filename, abs_filename = hovered_item.filename, hovered_item.abs_filename
-        local index = string.find(abs_filename, filename, 1, true)
+        local index = 0
+        -- The loop below is used to find the first match starting from the end
+        -- in case there are multiple matches.
+        while index and index + #filename < #abs_filename do
+          index = string.find(abs_filename, filename, index + 1, true)
+        end
+        -- we assume here index is not nil because the abs_filename must contain the
+        -- relative filename
         local dirname = string.sub(abs_filename, 1, index - 2)
-        core.scan_project_folder(dirname, filename)
-        self:invalidate_cache(dirname)
+        if core.is_project_folder(dirname) then
+          core.scan_project_folder(dirname, filename)
+          self:invalidate_cache(dirname)
+        end
       end
       hovered_item.expanded = not hovered_item.expanded
     end