diff --git a/Dockerfile b/Dockerfile
index a0fc4d29..79d09353 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -85,6 +85,7 @@ RUN \
   rm -rf /var/lib/apt/lists/* && \
   c_rehash 2>&1
 
+COPY ./target/scripts/helpers/log.sh /usr/local/bin/helpers/log.sh
 COPY ./target/bin/sedfile /usr/local/bin/sedfile
 
 RUN chmod +x /usr/local/bin/sedfile
diff --git a/target/bin/sedfile b/target/bin/sedfile
index 3b849e07..6b550bff 100755
--- a/target/bin/sedfile
+++ b/target/bin/sedfile
@@ -9,6 +9,17 @@
 # Is a file change expected? --> use 'sedfile --strict -i'
 # Is a file change only on the first container run expected? --> use 'sedfile -i'
 
+if [[ -e /usr/local/bin/helpers/log.sh ]]
+then
+  # shellcheck source=../scripts/helpers/log.sh
+  source /usr/local/bin/helpers/log.sh
+else
+  # when running BATS (unit tests), this file is not located
+  # inside a container; as a consequence, we need to source
+  # from a different location
+  source target/scripts/helpers/log.sh
+fi
+
 set -ueo pipefail
 
 function __usage { echo "Usage: ${0} -i <replace/delete operation> <file>" ; }
@@ -18,9 +29,8 @@ SKIP_ERROR=0
 
 if [[ ${#} -lt 3 ]]
 then
-  echo 'Error: At least three parameters must be given'
+  _log 'error' 'At least three parameters must be given'
   __usage
-  echo
   exit 1
 fi >&2
 
@@ -41,7 +51,7 @@ NEW=$(${HASHTOOL} "${FILE}")
 # fail if file was not modified
 if [[ ${OLD} == "${NEW}" ]] && [[ ${SKIP_ERROR} -eq 0 ]]
 then
-  echo "Error: No difference after call to 'sed' in 'sedfile' (sed ${*})" >&2
+  _log 'error' "No difference after call to 'sed' in 'sedfile' (sed ${*})" >&2
   exit 1
 fi
 
diff --git a/test/sedfile.bats b/test/sedfile.bats
index 61b49ccf..4cc3ee89 100644
--- a/test/sedfile.bats
+++ b/test/sedfile.bats
@@ -18,7 +18,7 @@ function setup_file() {
 @test "checking sedfile parameter count" {
   run ${SEDFILE}
   assert_failure
-  assert_output --partial 'Error: At least three parameters must be given'
+  assert_output --partial 'At least three parameters must be given'
 }
 
 @test "checking sedfile substitute success" {
@@ -35,7 +35,7 @@ function setup_file() {
 @test "checking sedfile substitute failure" {
   run ${SEDFILE} -i 's|bar|baz|' "${FILE}"
   assert_failure
-  assert_output --partial "Error: No difference after call to 'sed' in 'sedfile' (sed -i s|bar|baz| /tmp/sedfile-test"
+  assert_output --partial "No difference after call to 'sed' in 'sedfile' (sed -i s|bar|baz| /tmp/sedfile-test"
 
   # file unchanged?
   run test "$(< "${FILE}")" == 'foo baz'
@@ -58,7 +58,7 @@ function setup_file() {
 @test "checking sedfile substitude failure (strict)" {
   run ${SEDFILE} --strict -i 's|bar|baz|' "${FILE}"
   assert_failure
-  assert_output --partial "Error: No difference after call to 'sed' in 'sedfile' (sed -i s|bar|baz| /tmp/sedfile-test"
+  assert_output --partial "No difference after call to 'sed' in 'sedfile' (sed -i s|bar|baz| /tmp/sedfile-test"
 
   # file unchanged?
   run test "$(< "${FILE}")" == 'foo baz'