diff --git a/DESCRIPTION b/DESCRIPTION
index 261e25c..42a8a58 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -2,8 +2,10 @@ Package: RCzechia
 Type: Package
 Title: Spatial Objects of the Czech Republic
 Version: 1.9.4
-Date: 2022-07-14
-Author: Jindra Lacko
+Date: 2022-10-06
+Authors@R: 
+    person("Jindra", "Lacko", , "jindra.lacko@gmail.com", role = c("aut", "cre"),
+    comment = c(ORCID = "0000-0002-0375-5156"))
 Maintainer: Jindra Lacko <jindra.lacko@gmail.com>
 Description: Administrative regions and other spatial objects of the Czech Republic.
 URL: https://github.com/jlacko/RCzechia
@@ -40,6 +42,6 @@ SystemRequirements:
   GDAL (>= 2.2.3), 
   GEOS (>= 3.6.2),
   PROJ (>= 4.9.3)
-RoxygenNote: 7.2.0
+RoxygenNote: 7.2.1
 VignetteBuilder: knitr
 NeedsCompilation: no
diff --git a/NEWS.md b/NEWS.md
index 0419d3a..52e7752 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,3 +1,9 @@
+## version 1.9.4
+
+ - fixes incorrect behavior of Vltava in Prague
+ 
+ - internal optimization in line with updated dependencies
+
 ## version 1.9.3 (2022-06-03)
  
  - fixes naming conflict between Lužnice proper (a major river) and Lužnice - tributary of Mastník (a tiny brook by Sedlčany).
diff --git a/R/sysdata.rda b/R/sysdata.rda
index 3157230..69860c6 100644
Binary files a/R/sysdata.rda and b/R/sysdata.rda differ
diff --git a/data-raw/Dockerfile b/data-raw/Dockerfile
index d2fc76c..75cc511 100644
--- a/data-raw/Dockerfile
+++ b/data-raw/Dockerfile
@@ -43,22 +43,29 @@ RUN apt-get update && apt-get -y install libjq-dev
 RUN apt-get update && apt-get -y install libprotobuf-dev
 RUN apt-get update && apt-get -y install protobuf-compiler
 RUN apt-get update && apt-get -y install libxtst6
+RUN apt-get update && apt-get -y install libfontconfig1-dev
+RUN apt-get update && apt-get -y install libharfbuzz-dev
+RUN apt-get update && apt-get -y install libfribidi-dev
+RUN apt-get update && apt-get -y install libfreetype6-dev
+RUN apt-get update && apt-get -y install libpng-dev
+RUN apt-get update && apt-get -y install libtiff5-dev
+RUN apt-get update && apt-get -y install libjpeg-dev
 RUN ldconfig
 
 # and finally! set up R packages / frozen in time to keep consistent
-RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2021-12-31')); if(!require('devtools')) install.packages(c('devtools'))"
-RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2021-12-31')); if(!require('dplyr')) install.packages(c('dplyr'))"
-RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2021-12-31')); if(!require('sp')) install.packages(c('sp'))"
-RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2021-12-31')); if(!require('lwgeom')) install.packages(c('lwgeom'))"
-RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2021-12-31')); if(!require('sf')) install.packages(c('sf'))"
-RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2021-12-31')); if(!require('czso')) install.packages(c('czso'))"
-RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2021-12-31')); if(!require('BH')) install.packages(c('BH'))"
-RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2021-12-31')); if(!require('data.table')) install.packages(c('data.table'))"
-RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2021-12-31')); if(!require('nngeo')) install.packages(c('nngeo'))"
-RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2021-12-31')); if(!require('rmapshaper')) install.packages(c('rmapshaper'))"
-RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2021-12-31')); if(!require('ggplot2')) install.packages(c('ggplot2'))"
-RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2021-12-31')); if(!require('usethis')) install.packages(c('usethis'))"
-RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2021-12-31')); if(!require('rlang')) install.packages(c('rlang'))"
+RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2022-09-30')); if(!require('devtools')) install.packages(c('devtools'))"
+RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2022-09-30')); if(!require('dplyr')) install.packages(c('dplyr'))"
+RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2022-09-30')); if(!require('sp')) install.packages(c('sp'))"
+RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2022-09-30')); if(!require('lwgeom')) install.packages(c('lwgeom'))"
+RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2022-09-30')); if(!require('sf')) install.packages(c('sf'))"
+RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2022-09-30')); if(!require('czso')) install.packages(c('czso'))"
+RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2022-09-30')); if(!require('BH')) install.packages(c('BH'))"
+RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2022-09-30')); if(!require('data.table')) install.packages(c('data.table'))"
+RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2022-09-30')); if(!require('nngeo')) install.packages(c('nngeo'))"
+RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2022-09-30')); if(!require('rmapshaper')) install.packages(c('rmapshaper'))"
+RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2022-09-30')); if(!require('ggplot2')) install.packages(c('ggplot2'))"
+RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2022-09-30')); if(!require('usethis')) install.packages(c('usethis'))"
+RUN R -e "options(repos = list(CRAN = 'http://mran.revolutionanalytics.com/snapshot/2022-09-30')); if(!require('rlang')) install.packages(c('rlang'))"
 
 # bleeding edge RCzechia, current CRAN (not really frozen in time, but under control)
 RUN R -e "install.packages('RCzechia')"
diff --git a/data-raw/lo-res-polygons.R b/data-raw/lo-res-polygons.R
index a5c17ee..350c609 100644
--- a/data-raw/lo-res-polygons.R
+++ b/data-raw/lo-res-polygons.R
@@ -10,7 +10,6 @@ for (kod in unique(okresy_low_res$KOD_CZNUTS3)) {
     st_union() %>%
     st_sf() %>%
     nngeo::st_remove_holes() %>%
-    rename(geometry = geom) %>%
     mutate(
       KOD_KRAJ = unique(okresy_low_res$KOD_KRAJ[okresy_low_res$KOD_CZNUTS3 == kod]),
       KOD_CZNUTS3 = unique(okresy_low_res$KOD_CZNUTS3[okresy_low_res$KOD_CZNUTS3 == kod]),
@@ -28,8 +27,6 @@ for (kod in unique(okresy_low_res$KOD_CZNUTS3)) {
   }
 }
 
-st_geometry(kraje_low_res) <- "geometry"
-
 # ze STČ vyříznout Prahu
 kraje_low_res[kraje_low_res$KOD_KRAJ=="3026",] <- st_difference(kraje_low_res[kraje_low_res$KOD_KRAJ=="3026",], st_geometry(kraje_low_res[kraje_low_res$KOD_KRAJ=="3018",]))
 
@@ -57,10 +54,8 @@ st_geometry(okresy_low_res) <- geometrie
 
 republika_low_res <- okresy_low_res %>% # select the non-central parts
   summarize(NAZ_STAT = republika()$NAZ_STAT) %>% # return back the data value
-  nngeo::st_remove_holes() %>%
-  rename(geometry = geom)
+  nngeo::st_remove_holes()
 
-st_geometry(republika_low_res) <- "geometry"
 
 # úklid
 okresy_low_res <- st_transform(okresy_low_res, 4326) # WGS84
diff --git a/data-raw/reky_mesta.R b/data-raw/reky_mesta.R
index 01a825d..0000bb2 100644
--- a/data-raw/reky_mesta.R
+++ b/data-raw/reky_mesta.R
@@ -1,7 +1,7 @@
 
 okresy <- readRDS("./data-backup/Okresy-R-2021-01.rds")
 
-reky <- readRDS("./data-backup/Reky-D200-2021-07.rds") %>%
+reky <- readRDS("./data-backup/Reky.rds") %>%
   select(NAZEV)
 
 brno <- okresy %>%
@@ -14,6 +14,7 @@ svitava_brno <- reky %>%
   st_intersection(st_buffer(brno, 1200)) %>%
   st_transform(4326) %>%
   st_geometry() %>%
+  st_union() %>%
   st_as_sf() %>%
   mutate(NAZEV = "Svitava")
 
@@ -23,6 +24,7 @@ svratka_brno <- reky %>%
   st_intersection(st_buffer(brno, 1200)) %>%
   st_transform(4326) %>%
   st_geometry() %>%
+  st_union() %>%
   st_as_sf() %>%
   mutate(NAZEV = "Svratka")
 
@@ -44,7 +46,7 @@ reky_praha <- reky %>%
   st_transform(4326) %>%
   st_geometry() %>%
   st_union() %>%
-  st_line_merge() %>%
+#  st_line_merge() %>%
   st_as_sf() %>%
   mutate(NAZEV = "Vltava")
 
diff --git a/tests/testthat/test-3-integrace.R b/tests/testthat/test-3-integrace.R
index 552ee2c..16f5b1b 100644
--- a/tests/testthat/test-3-integrace.R
+++ b/tests/testthat/test-3-integrace.R
@@ -133,5 +133,25 @@ test_that("dopady 51/2020 Sb.", {
   expect_equal(st_join(veznice, orp_polygony(), left = F)$KOD_ORP, "6102") # Havlíčkův Brod
 })
 
+test_that("Vltava dělí Prahu na dvě půlky", {
+
+  skip_on_cran()
+
+  # polygon Praha
+  praha <- kraje() %>%
+    filter(KOD_CZNUTS3 == "CZ010")
+
+  # řeka Vltava
+  reka <- reky("Praha")
+
+  # Praha říznutá na půlky
+  pulky <- praha %>%
+    st_geometry() %>%
+    lwgeom::st_split(reka) %>% # polygon říznutý čárou
+    st_cast()
+
+  expect_equal(length(pulky), 2) # dvě půlky z jednoho celku
+
+})