diff --git a/Dockerfile-alpine3.10 b/Dockerfile-alpine3.10
index 1b7aec02..f6b64dec 100644
--- a/Dockerfile-alpine3.10
+++ b/Dockerfile-alpine3.10
@@ -32,7 +32,7 @@ RUN CGO_ENABLED=1 \
 
 # build final image
 FROM alpine:3.10
-RUN apk --no-cache add ca-certificates jq bash && \
+RUN apk --no-cache add ca-certificates jq bash sed && \
     wget https://storage.googleapis.com/kubernetes-release/release/v1.17.4/bin/linux/amd64/kubectl -O /bin/kubectl && \
     chmod +x /bin/kubectl && \
     mkdir /hooks
diff --git a/Dockerfile-alpine3.11 b/Dockerfile-alpine3.11
index b69b78d6..464b06a5 100644
--- a/Dockerfile-alpine3.11
+++ b/Dockerfile-alpine3.11
@@ -32,7 +32,7 @@ RUN CGO_ENABLED=1 \
 
 # build final image
 FROM alpine:3.11
-RUN apk --no-cache add ca-certificates jq bash && \
+RUN apk --no-cache add ca-certificates jq bash sed && \
     wget https://storage.googleapis.com/kubernetes-release/release/v1.17.4/bin/linux/amd64/kubectl -O /bin/kubectl && \
     chmod +x /bin/kubectl && \
     mkdir /hooks
diff --git a/Dockerfile-alpine3.9 b/Dockerfile-alpine3.9
index b776d528..920d1df3 100644
--- a/Dockerfile-alpine3.9
+++ b/Dockerfile-alpine3.9
@@ -32,7 +32,7 @@ RUN CGO_ENABLED=1 \
 
 # build final image
 FROM alpine:3.9
-RUN apk --no-cache add ca-certificates jq bash && \
+RUN apk --no-cache add ca-certificates jq bash sed && \
     wget https://storage.googleapis.com/kubernetes-release/release/v1.17.4/bin/linux/amd64/kubectl -O /bin/kubectl && \
     chmod +x /bin/kubectl && \
     mkdir /hooks
diff --git a/frameworks/shell/context.sh b/frameworks/shell/context.sh
index a80d0f9c..e40b3b0f 100644
--- a/frameworks/shell/context.sh
+++ b/frameworks/shell/context.sh
@@ -68,7 +68,7 @@ function context::_convert_user_path_to_jq_path() {
   # loop3 — convert array addresation from myArray.0 to myArray[0]
   # loop4 — return original dots from ##DOT##, i.e. aaa."bb##DOT##bb".cc -> aa."bb.bb".cc
 
-  jqPath=".$(sed -r \
+  jqPath=".$(sed -E \
     -e s/\'/\"/g \
     -e ':loop1' -e 's/"([^".]+)\.([^"]+)"/"\1##DOT##\2"/g' -e 't loop1' \
     -e ':loop2' -e 's/(^|\.)([^."]*-[^."]*)(\.|$)/\1"\2"\3/g' -e 't loop2' \
@@ -81,16 +81,16 @@ function context::_convert_user_path_to_jq_path() {
 
 function context::_dirname() {
   # loop1 — hide dots in keys, i.e. aaa."bb.bb".ccc -> aaa."bb##DOT##bb".cc
-  splittable_path="$(sed -r -e s/\'/\"/g -e ':loop1' -e 's/"([^".]+)\.([^"]+)"/"\1##DOT##\2"/g' -e 't loop1' <<< ${1:-})"
+  splittable_path="$(sed -E -e s/\'/\"/g -e ':loop1' -e 's/"([^".]+)\.([^"]+)"/"\1##DOT##\2"/g' -e 't loop1' <<< ${1:-})"
 
   # loop2 — return original dots from ##DOT##, i.e. aaa."bb##DOT##bb".cc -> aa."bb.bb".cc
-  rev <<< "${splittable_path}" | cut -d. -f2- | rev | sed -r -e ':loop2' -e 's/(^|\.)"([^"]+)##DOT##([^"]+)"(\.|$)/\1"\2.\3"\4/g' -e 't loop2'
+  rev <<< "${splittable_path}" | cut -d. -f2- | rev | sed -E -e ':loop2' -e 's/(^|\.)"([^"]+)##DOT##([^"]+)"(\.|$)/\1"\2.\3"\4/g' -e 't loop2'
 }
 
 function context::_basename() {
   # loop1 — hide dots in keys, i.e. aaa."bb.bb".ccc -> aaa."bb##DOT##bb".cc
-  splittable_path="$(sed -r -e s/\'/\"/g -e ':loop1' -e 's/"([^".]+)\.([^"]+)"/"\1##DOT##\2"/g' -e 't loop1' <<< ${1:-})"
+  splittable_path="$(sed -E -e s/\'/\"/g -e ':loop1' -e 's/"([^".]+)\.([^"]+)"/"\1##DOT##\2"/g' -e 't loop1' <<< ${1:-})"
 
   # loop2 — return original dots from ##DOT##, i.e. "bb##DOT##bb" -> bb.bb
-  rev <<< "${splittable_path}" | cut -d. -f1 | rev | sed -r -e ':loop2' -e 's/^"([^"]+)##DOT##([^"]+)"$/\1.\2/g' -e 't loop2'
+  rev <<< "${splittable_path}" | cut -d. -f1 | rev | sed -E -e ':loop2' -e 's/^"([^"]+)##DOT##([^"]+)"$/\1.\2/g' -e 't loop2'
 }
diff --git a/frameworks/shell/hook.sh b/frameworks/shell/hook.sh
index 9a1927d7..d8902b5b 100644
--- a/frameworks/shell/hook.sh
+++ b/frameworks/shell/hook.sh
@@ -58,6 +58,6 @@ function hook::_run_first_available_handler() {
     fi
   done
 
-  >&2 printf "ERROR: Can't find any handler from the list: %s\n." "$(echo ${HANDLERS} | sed -re 's/\s+/, /g')"
+  >&2 printf "ERROR: Can't find any handler from the list: %s\n." "$(echo ${HANDLERS} | sed -E 's/[[:space:]]+/, /g')"
   return 1
 }