diff --git a/.travis.yml b/.travis.yml
index 74ecc20b6..af9b8f54c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -14,15 +14,20 @@ before_install:
     - sudo apt-get update
 
 install:
+    # nasm for building libpng, xutils-dev for building openssl with clang
     - sudo apt-get install libsdl1.2-dev luarocks nasm xutils-dev
-    - sudo luarocks install busted
+    # install an older version of lua_cliargs for busted v1.10.0
+    - sudo luarocks install lua_cliargs 2.1-2
+    # recent versions of busted may cause some weird segmentation faults
+    - git clone https://github.com/Olivine-Labs/busted/
+    - cd busted && git checkout v1.10.0 && sudo luarocks make && cd ..
 
 script:
     - make fetchthirdparty all
-    - sudo cp build/*/luajit /usr/bin/
-    - sudo ln -sf /usr/bin/luajit /usr/bin/lua
+    # install tesseract trained language data for testing OCR functionality
     - wget https://tesseract-ocr.googlecode.com/files/tesseract-ocr-3.02.eng.tar.gz
     - tar zxf tesseract-ocr-3.02.eng.tar.gz
     - cd build/* && export TESSDATA_PREFIX=`pwd`/data && mkdir -p data/tessdata
     - mv ../../tesseract-ocr/tessdata/* data/tessdata/ && cd ../../
+    # finally make test
     - make test
diff --git a/Makefile b/Makefile
index 3fd3815c7..6720644fb 100644
--- a/Makefile
+++ b/Makefile
@@ -671,6 +671,6 @@ $(OUTPUT_DIR)/spec/base:
 		ln -sf ../../../spec $(OUTPUT_DIR)/spec/base
 
 test: $(OUTPUT_DIR)/spec $(OUTPUT_DIR)/.busted
-	cd $(OUTPUT_DIR) && busted --exclude-tags=notest
+	cd $(OUTPUT_DIR) && busted -l ./luajit
 
 .PHONY: test
diff --git a/ffi/blitbuffer.lua b/ffi/blitbuffer.lua
index 61cfa985b..d19abdb5a 100644
--- a/ffi/blitbuffer.lua
+++ b/ffi/blitbuffer.lua
@@ -17,6 +17,7 @@ local intt = ffi.typeof("int")
 local uint32pt = ffi.typeof("uint32_t*")
 local uint8pt = ffi.typeof("uint8_t*")
 local posix = require("ffi/posix_h")
+local debug = debug
 
 -- the following definitions are redundant.
 -- they need to be since only this way we can set
@@ -701,6 +702,8 @@ end
 
 function BB_mt.__index:blitDefault(dest, dest_x, dest_y, offs_x, offs_y, width, height, setter, set_param)
     -- slow default variant:
+    local hook, mask, count = debug.gethook()
+    debug.sethook()
     local o_y = offs_y
     for y = dest_y, dest_y+height-1 do
         local o_x = offs_x
@@ -710,6 +713,7 @@ function BB_mt.__index:blitDefault(dest, dest_x, dest_y, offs_x, offs_y, width,
         end
         o_y = o_y + 1
     end
+    debug.sethook(hook, mask)
 end
 -- no optimized blitting by default:
 BB_mt.__index.blitTo4 = BB_mt.__index.blitDefault
@@ -797,6 +801,8 @@ PAINTING
 fill the whole blitbuffer with a given color value
 --]]
 function BB_mt.__index:fill(value)
+    local hook, mask, count = debug.gethook()
+    debug.sethook()
     local w = self:getWidth()
     local h = self:getHeight()
     for y = 0, h-1 do
@@ -804,6 +810,7 @@ function BB_mt.__index:fill(value)
             self:setPixel(x, y, value)
         end
     end
+    debug.sethook(hook, mask)
 end
 function BB4_mt.__index:fill(value)
     local v = value:getColor4L().a
@@ -837,6 +844,8 @@ paint a rectangle onto this buffer
 @param setter function used to set pixels (defaults to normal setPixel)
 --]]
 function BB_mt.__index:paintRect(x, y, w, h, value, setter)
+    local hook, mask, count = debug.gethook()
+    debug.sethook()
     setter = setter or self.setPixel
     value = value or Color8(0)
     if w <= 0 or h <= 0 then return end
@@ -847,6 +856,7 @@ function BB_mt.__index:paintRect(x, y, w, h, value, setter)
             setter(self, x, y, value)
         end
     end
+    debug.sethook(hook, mask)
 end
 
 --[[
@@ -1131,6 +1141,8 @@ see http://netpbm.sourceforge.net/doc/pam.html for PAM file specs.
 @param filename the name of the file to be created
 --]]
 function BB_mt.__index:writePAM(filename)
+    local hook, mask, count = debug.gethook()
+    debug.sethook()
     local f = io.open(filename, "w")
     f:write("P7\n")
     f:write("# written by blitbuffer.lua\n")
@@ -1185,6 +1197,7 @@ function BB_mt.__index:writePAM(filename)
         end
     end
     f:close()
+    debug.sethook(hook, mask)
 end
 
 --[[
@@ -1193,6 +1206,8 @@ write blitbuffer contents to a PNG file
 @param filename the name of the file to be created
 --]]
 function BB_mt.__index:writePNG(filename)
+    local hook, mask, count = debug.gethook()
+    debug.sethook()
     require("ffi/leptonica_h")
     local lept = nil
     if ffi.os == "Windows" then
@@ -1211,6 +1226,7 @@ function BB_mt.__index:writePNG(filename)
         lept.pixWritePng(filename, pix, ffi.new("float", 0.0))
         lept.pixDestroy(ffi.new('PIX *[1]', pix))
     end
+    debug.sethook(hook, mask)
 end
 
 -- if no special case in BB???_mt exists, use function from BB_mt
diff --git a/ffi/mupdf.lua b/ffi/mupdf.lua
index aaf2699b6..8d709099d 100644
--- a/ffi/mupdf.lua
+++ b/ffi/mupdf.lua
@@ -676,6 +676,8 @@ only 8bit+8bit alpha or 24bit+8bit alpha pixmaps. So we need to convert
 what we get from mupdf.
 --]]
 local function bmpmupdf_pixmap_to_bmp(bmp, pixmap)
+    local hook, mask, count = debug.gethook()
+    debug.sethook()
     local k2pdfopt = get_k2pdfopt()
 
     bmp.width = M.fz_pixmap_width(context(), pixmap)
@@ -719,8 +721,10 @@ local function bmpmupdf_pixmap_to_bmp(bmp, pixmap)
             end
         end
     else
+        debug.sethook(hook, mask)
         error("unsupported pixmap format for conversion to bmp")
     end
+    debug.sethook(hook, mask)
 end
 
 local function render_for_kopt(bmp, page, scale, bounds)