diff --git a/.Rbuildignore b/.Rbuildignore
index 144e1b7..72bc654 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -26,3 +26,4 @@ cmake-build-debug$
 ^codecov\.yml$
 ^_pkgdown\.yml$
 ^docs$
+^docker$
diff --git a/.gitignore b/.gitignore
index 596c1d5..f6e5a0b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,3 +18,4 @@
 /CMakeLists.txt
 /clion-test.R
 /cmake-build-debug/
+*~
diff --git a/.travis.yml b/.travis.yml
index 04e98a1..c744921 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,29 +1,25 @@
-# R for travis: see documentation at https://docs.travis-ci.com/user/languages/r
+os: linux
+services: docker
+
+before_install:
+  - make docker-pull
+  - make info
 
-language: R
-sudo: false
-cache: packages
-os:
-  - linux
-r:
-  - oldrel
-  - release
-  - devel
 notifications:
   email:
     on_success: change
     on_failure: change
+
 addons:
   apt:
     packages:
-    - texlive-xetex
-    - texlive-latex-extra
-    - texlive-fonts-recommended
-    - texlive-pictures
-    - ghostscript
-    - qpdf
-r_packages:
-  - covr
-r_build_args: --compact-vignettes=gs+qpdf
+    - make
+
+install:
+  - make build
+
+script:
+  - make check test
+
 after_success:
-  - test "$TRAVIS_R_VERSION_STRING" = "release" && Rscript -e 'covr::codecov()' || true
+  - make covr
diff --git a/DESCRIPTION b/DESCRIPTION
index a73adb9..842e306 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -40,5 +40,5 @@ Suggests:
 SystemRequirements: pgf (>= 2.00)
 LazyLoad: yes
 VignetteBuilder: knitr
-RoxygenNote: 6.1.0
+RoxygenNote: 6.1.1
 Roxygen: list(markdown = TRUE)
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..0936eb0
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,41 @@
+SUDO := $(shell groups | grep -q docker || echo sudo -E)
+IMAGE := "tikzdevice/ci"
+PWD := $(shell pwd)
+UID := $(shell id -u):$(shell id -g)
+
+DOCKER_OPTS := --rm -u $(UID) -e HOME=/tmp -v $(PWD):/mnt -w /mnt
+
+PKG_VERSION = $(shell grep -i ^version DESCRIPTION | cut -d : -d \  -f 2)
+PKG_NAME = $(shell grep -i ^package DESCRIPTION | cut -d : -d \  -f 2)
+PKG_TAR = $(PKG_NAME)_$(PKG_VERSION).tar.gz
+
+all: build check test clean
+
+docker-build:
+	$(SUDO) docker build -t $(IMAGE) docker
+
+docker-pull:
+	$(SUDO) docker pull $(IMAGE)
+
+docker-push:
+	$(SUDO) docker push $(IMAGE)
+
+
+info:
+	$(SUDO) docker run $(DOCKER_OPTS) $(IMAGE) Rscript -e "sessionInfo()"
+
+build:
+	$(SUDO) docker run $(DOCKER_OPTS) $(IMAGE) R CMD build --compact-vignettes=gs+qpdf .
+
+check:
+	$(SUDO) docker run $(DOCKER_OPTS) $(IMAGE) R CMD check --no-manual $(PKG_TAR)
+
+test:
+	$(SUDO) docker run $(DOCKER_OPTS) $(IMAGE) Rscript -e \
+	   'install.packages("$(PKG_TAR)", repos = NULL); testthat::test_dir("tests", stop_on_failure = TRUE)'
+
+covr:
+	$(SUDO) docker run $(DOCKER_OPTS) -e CODECOV_TOKEN $(IMAGE) Rscript -e "covr::codecov()"
+
+clean:
+	rm -rf $(PKG_TAR) $(PKG_NAME).Rcheck/
diff --git a/docker/Dockerfile b/docker/Dockerfile
new file mode 100644
index 0000000..043e70e
--- /dev/null
+++ b/docker/Dockerfile
@@ -0,0 +1,29 @@
+FROM rocker/r-ver:latest
+
+LABEL org.label-schema.license="GPL-2.0" \
+      org.label-schema.vcs-url="https://github.com/daqana/tikzDevice" \
+      maintainer="Ralf Stubner <ralf.stubner@daqana.com>"
+
+RUN apt-get update \
+ && apt-get install --yes --no-install-recommends \
+            ghostscript \
+            git \
+            imagemagick \
+            libcurl4-openssl-dev \
+            libpng-dev \
+            libssl-dev \
+            perl \
+            qpdf \
+            texinfo \
+            wget \
+ && wget -qO- "https://yihui.name/gh/tinytex/tools/install-unx.sh" \
+         | sh -s - --admin --no-path \
+ && mv ~/.TinyTeX /usr/local/tinytex \
+ && /usr/local/tinytex/bin/*/tlmgr path add \
+ && tlmgr install pgf preview xcolor memoir ifetex microtype float \
+                  babel-english listings xstring luatex85 \
+ && install2.r filehash png evaluate formatR ggplot2 knitr lattice maps \
+               testthat tinytex covr \
+ && rm -rf /var/lib/apt/lists/* \
+ && rm -rf /tmp/* \
+ && chmod 777 /usr/local/lib/R/site-library
diff --git a/src/tikzDevice.c b/src/tikzDevice.c
index 42b40f4..f27fe30 100644
--- a/src/tikzDevice.c
+++ b/src/tikzDevice.c
@@ -1368,14 +1368,22 @@ static void TikZ_Polyline( int n, double *x, double *y,
 
   /* End options, print first set of coordinates. */
   printOutput(tikzInfo, "] (%6.2f,%6.2f) --\n",
-    x[0],y[0]);
+              x[0],y[0]);
+
+  /*Show only for debugging*/
+  if(tikzInfo->debug == TRUE)
+    printOutput(tikzInfo, "%% First point x = %f, y = %f\n", x[0],y[0]);
 
   /* Print coordinates for the middle segments of the line. */
   int i;
   for ( i = 1; i < n-1; i++ ){
 
     printOutput(tikzInfo, "\t(%6.2f,%6.2f) --\n",
-      x[i],y[i]);
+                x[i],y[i]);
+
+    /*Show only for debugging*/
+    if(tikzInfo->debug == TRUE)
+      printOutput(tikzInfo, "%% Next point x = %f, y = %f\n", x[i],y[i]);
 
   }
 
@@ -1383,6 +1391,10 @@ static void TikZ_Polyline( int n, double *x, double *y,
   printOutput(tikzInfo, "\t(%6.2f,%6.2f);\n",
     x[n-1],y[n-1]);
 
+  /*Show only for debugging*/
+  if(tikzInfo->debug == TRUE)
+    printOutput(tikzInfo, "%% Final point x = %f, y = %f\n", x[n-1],y[n-1]);
+
   /*Show only for debugging*/
   if(tikzInfo->debug == TRUE)
     printOutput(tikzInfo,
@@ -1415,6 +1427,10 @@ static void TikZ_Polygon( int n, double *x, double *y,
   printOutput(tikzInfo, "] (%6.2f,%6.2f) --\n",
     x[0],y[0]);
 
+  /*Show only for debugging*/
+  if(tikzInfo->debug == TRUE)
+    printOutput(tikzInfo, "%% First point x = %f, y = %f\n", x[0],y[0]);
+
   /* Print coordinates for the middle segments of the line. */
   int i;
   for ( i = 1; i < n; i++ ){
@@ -1422,6 +1438,10 @@ static void TikZ_Polygon( int n, double *x, double *y,
     printOutput(tikzInfo, "\t(%6.2f,%6.2f) --\n",
       x[i],y[i]);
 
+    /*Show only for debugging*/
+    if(tikzInfo->debug == TRUE)
+      printOutput(tikzInfo, "%% Next point x = %f, y = %f\n", x[i],y[i]);
+
   }
 
   /* End path by cycling to first set of coordinates. */
@@ -1430,7 +1450,7 @@ static void TikZ_Polygon( int n, double *x, double *y,
   /*Show only for debugging*/
   if(tikzInfo->debug == TRUE)
     printOutput(tikzInfo,
-      "%% End Polyline\n");
+      "%% End Polygon\n");
 
 }
 
diff --git a/tests/testthat/helper_graphics.R b/tests/testthat/helper_graphics.R
index 4723b4b..096bfd9 100644
--- a/tests/testthat/helper_graphics.R
+++ b/tests/testthat/helper_graphics.R
@@ -127,11 +127,10 @@ compare_graph <- function(graph_name, tags) {
     return(TRUE)
   }
 
-
   # Normalize and quote some paths in case we are running on Windows
   compare_output <- file.path(test_work_dir, paste0(graph_name, "_diff.png"))
   command_line <- paste(
-    shQuote(compare_cmd), "-density 300", "-metric AE",
+    shQuote(compare_cmd), "-density 300", "-metric AE", "-quiet",
     shQuote(test_output), shQuote(standard_graph), shQuote(compare_output),
     "2>&1 | awk '{metric=$NF};END{print metric}'"
   )
diff --git a/tests/testthat/standard_graphs/ggplot2_superscripts.pdf b/tests/testthat/standard_graphs/ggplot2_superscripts.pdf
index a8f4f7c..52f3406 100644
Binary files a/tests/testthat/standard_graphs/ggplot2_superscripts.pdf and b/tests/testthat/standard_graphs/ggplot2_superscripts.pdf differ
diff --git a/tests/testthat/standard_graphs/ggplot2_test.pdf b/tests/testthat/standard_graphs/ggplot2_test.pdf
index ff297cb..d644dee 100644
Binary files a/tests/testthat/standard_graphs/ggplot2_test.pdf and b/tests/testthat/standard_graphs/ggplot2_test.pdf differ
diff --git a/tests/testthat/standard_graphs/luatex_utf8_characters.pdf b/tests/testthat/standard_graphs/luatex_utf8_characters.pdf
index a342154..dd350ba 100644
Binary files a/tests/testthat/standard_graphs/luatex_utf8_characters.pdf and b/tests/testthat/standard_graphs/luatex_utf8_characters.pdf differ
diff --git a/tests/testthat/standard_graphs/utf8_characters.pdf b/tests/testthat/standard_graphs/utf8_characters.pdf
index ba0e00e..492528e 100644
Binary files a/tests/testthat/standard_graphs/utf8_characters.pdf and b/tests/testthat/standard_graphs/utf8_characters.pdf differ
diff --git a/tests/testthat/test_metrics_dict.R b/tests/testthat/test_metrics_dict.R
index 54eae51..08ad01f 100644
--- a/tests/testthat/test_metrics_dict.R
+++ b/tests/testthat/test_metrics_dict.R
@@ -4,8 +4,8 @@ test_that("Temporary metrics dictionary is created, but only once", {
   expect_equal(getOption("tikzMetricsDictionary"), NULL)
 
   rm(list = ls(envir = .tikzInternal), envir = .tikzInternal)
-  expect_that(checkDictionaryStatus(verbose = TRUE), shows_message("Creating"))
-  expect_that(checkDictionaryStatus(verbose = TRUE), not(shows_message()))
+  expect_message(checkDictionaryStatus(verbose = TRUE), "Creating")
+  expect_silent(checkDictionaryStatus(verbose = TRUE))
   expect_true(file.exists(.tikzInternal[["db_file"]]))
 })
 
@@ -13,8 +13,8 @@ test_that("Silent creation of temporary metrics dictionary", {
   expect_equal(getOption("tikzMetricsDictionary"), NULL)
 
   rm(list = ls(envir = .tikzInternal), envir = .tikzInternal)
-  expect_that(checkDictionaryStatus(verbose = FALSE), not(shows_message()))
-  expect_that(checkDictionaryStatus(verbose = FALSE), not(shows_message()))
+  expect_silent(checkDictionaryStatus(verbose = FALSE))
+  expect_silent(checkDictionaryStatus(verbose = FALSE))
   expect_true(file.exists(.tikzInternal[["db_file"]]))
 })
 
@@ -27,23 +27,23 @@ test_that("Switching metrics dictionary", {
   tryCatch(
     {
       options(tikzMetricsDictionary = tempA)
-      expect_that(checkDictionaryStatus(verbose = TRUE), shows_message("Creating"))
-      expect_that(checkDictionaryStatus(verbose = TRUE), not(shows_message()))
+      expect_message(checkDictionaryStatus(verbose = TRUE), "Creating")
+      expect_silent(checkDictionaryStatus(verbose = FALSE))
       options(tikzMetricsDictionary = tempB)
-      expect_that(checkDictionaryStatus(verbose = TRUE), shows_message("Creating"))
-      expect_that(checkDictionaryStatus(verbose = TRUE), not(shows_message()))
+      expect_message(checkDictionaryStatus(verbose = TRUE), "Creating")
+      expect_silent(checkDictionaryStatus(verbose = FALSE))
       options(tikzMetricsDictionary = tempA)
-      expect_that(checkDictionaryStatus(verbose = TRUE), shows_message("Using"))
-      expect_that(checkDictionaryStatus(verbose = TRUE), not(shows_message()))
+      expect_message(checkDictionaryStatus(verbose = TRUE), "Using")
+      expect_silent(checkDictionaryStatus(verbose = FALSE))
       options(tikzMetricsDictionary = tempB)
-      expect_that(checkDictionaryStatus(verbose = TRUE), shows_message("Using"))
-      expect_that(checkDictionaryStatus(verbose = TRUE), not(shows_message()))
+      expect_message(checkDictionaryStatus(verbose = TRUE), "Using")
+      expect_silent(checkDictionaryStatus(verbose = FALSE))
       options(tikzMetricsDictionary = tempA)
-      expect_that(checkDictionaryStatus(verbose = FALSE), not(shows_message()))
-      expect_that(checkDictionaryStatus(verbose = FALSE), not(shows_message()))
+      expect_silent(checkDictionaryStatus(verbose = FALSE))
+      expect_silent(checkDictionaryStatus(verbose = FALSE))
       options(tikzMetricsDictionary = tempB)
-      expect_that(checkDictionaryStatus(verbose = FALSE), not(shows_message()))
-      expect_that(checkDictionaryStatus(verbose = FALSE), not(shows_message()))
+      expect_silent(checkDictionaryStatus(verbose = FALSE))
+      expect_silent(checkDictionaryStatus(verbose = FALSE))
     },
     finally = {
       options(tikzMetricsDictionary = NULL)
@@ -61,17 +61,17 @@ test_that("Turning custom metrics dictionary on and off", {
   tryCatch(
     {
       options(tikzMetricsDictionary = temp)
-      expect_that(checkDictionaryStatus(verbose = TRUE), shows_message("Creating"))
-      expect_that(checkDictionaryStatus(verbose = TRUE), not(shows_message()))
+      expect_message(checkDictionaryStatus(verbose = TRUE), "Creating")
+      expect_silent(checkDictionaryStatus(verbose = FALSE))
       options(tikzMetricsDictionary = NULL)
-      expect_that(checkDictionaryStatus(verbose = TRUE), shows_message("Creating"))
-      expect_that(checkDictionaryStatus(verbose = TRUE), not(shows_message()))
+      expect_message(checkDictionaryStatus(verbose = TRUE), "Creating")
+      expect_silent(checkDictionaryStatus(verbose = FALSE))
       options(tikzMetricsDictionary = temp)
-      expect_that(checkDictionaryStatus(verbose = TRUE), shows_message("Using"))
-      expect_that(checkDictionaryStatus(verbose = TRUE), not(shows_message()))
+      expect_message(checkDictionaryStatus(verbose = TRUE), "Using")
+      expect_silent(checkDictionaryStatus(verbose = FALSE))
       options(tikzMetricsDictionary = NULL)
-      expect_that(checkDictionaryStatus(verbose = TRUE), shows_message("Creating"))
-      expect_that(checkDictionaryStatus(verbose = TRUE), not(shows_message()))
+      expect_message(checkDictionaryStatus(verbose = TRUE), "Creating")
+      expect_silent(checkDictionaryStatus(verbose = FALSE))
     },
     finally = {
       options(tikzMetricsDictionary = NULL)