diff --git a/frontend/document/credocument.lua b/frontend/document/credocument.lua
index 5b6abdad1..443e0ba02 100644
--- a/frontend/document/credocument.lua
+++ b/frontend/document/credocument.lua
@@ -9,6 +9,9 @@ local ffi = require("ffi")
 local lfs = require("libs/libkoreader-lfs")
 local logger = require("logger")
 
+-- engine can be initialized only once, on first document opened
+local engine_initialized = false
+
 local CreDocument = Document:new{
     -- this is defined in kpvcrlib/crengine/crengine/include/lvdocview.h
     SCROLL_VIEW_MODE = 0,
@@ -16,7 +19,6 @@ local CreDocument = Document:new{
 
     _document = false,
     _loaded = false,
-    engine_initilized = false,
 
     line_space_percent = 100,
     default_font = G_reader_settings:readSetting("cre_font") or "Noto Serif",
@@ -47,7 +49,7 @@ function CreDocument:cacheInit()
 end
 
 function CreDocument:engineInit()
-    if not self.engine_initilized then
+    if not engine_initialized then
         require "libs/libkoreader-cre"
         -- initialize cache
         self:cacheInit()
@@ -66,7 +68,7 @@ function CreDocument:engineInit()
             end
         end
 
-        self.engine_initilized = true
+        engine_initialized = true
     end
 end
 
diff --git a/frontend/document/documentregistry.lua b/frontend/document/documentregistry.lua
index 48bba2e84..027f95a7e 100644
--- a/frontend/document/documentregistry.lua
+++ b/frontend/document/documentregistry.lua
@@ -28,6 +28,11 @@ function DocumentRegistry:getProvider(file)
 end
 
 function DocumentRegistry:openDocument(file)
+    -- force a GC, so that any previous document used memory can be reused
+    -- immediately by this new document without having to wait for the
+    -- next regular gc. The second call may help reclaming more memory.
+    collectgarbage()
+    collectgarbage()
     if not self.registry[file] then
         local provider = self:getProvider(file)
         if provider ~= nil then