diff --git a/buildlib/az-helpers.sh b/buildlib/az-helpers.sh
index b3098edb138..814a516e05d 100644
--- a/buildlib/az-helpers.sh
+++ b/buildlib/az-helpers.sh
@@ -249,11 +249,12 @@ check_release_build() {
 
     elif [ "${build_reason}" == "PullRequest" ]
     then
-        # In case of pull request, HEAD^ is the branch commit we merge with
-        range="$(git rev-parse HEAD^)..${build_sourceversion}"
-        for sha1 in `git log $range --format="%h"`
+        base_revision=$(git rev-parse "${build_sourceversion}^1")
+        head_revision=$(git rev-parse "${build_sourceversion}^2")
+        for sha1 in $(git log --first-parent --no-merges \
+                         "${base_revision}..${head_revision}" --format="%h")
         do
-            title=`git log -1 --format="%s" $sha1`
+            title=$(git log -1 --format="%s" $sha1)
             [[ "$title" == "${title_mask}"* ]] && launch=True;
         done
     fi
diff --git a/buildlib/pr/codestyle.yml b/buildlib/pr/codestyle.yml
index 8295eea5dbb..f88b78aba67 100644
--- a/buildlib/pr/codestyle.yml
+++ b/buildlib/pr/codestyle.yml
@@ -18,10 +18,10 @@ jobs:
           set -eE
           source ./buildlib/tools/codestyle.sh
 
-          BASE_SOURCEVERSION=$(git rev-parse HEAD^)
-          range="$BASE_SOURCEVERSION..$(Build.SourceVersion)"
+          base_revision=$(git rev-parse "$(Build.SourceVersion)^1")
+          head_revision=$(git rev-parse "$(Build.SourceVersion)^2")
 
-          codestyle_check_commit_title "$range"
+          codestyle_check_commit_title "$base_revision..$head_revision"
           if [[ $? -ne 0 ]]
           then
               url="https://github.com/openucx/ucx/wiki/Guidance-for-contributors#general-guidelines"
@@ -85,11 +85,10 @@ jobs:
       - bash: |
           set -eEx
 
-          BASE_SOURCEVERSION=$(git rev-parse HEAD^)
-          range="$BASE_SOURCEVERSION..$(Build.SourceVersion)"
+          base_revision=$(git rev-parse "$(Build.SourceVersion)^1")
+          head_revision=$(git rev-parse "$(Build.SourceVersion)^2")
 
-          echo "Looking for missing AUTHORS on commit range ${range}"
-          ./contrib/authors_update.sh "$range"
+          ./contrib/authors_update.sh "$base_revision..$head_revision"
           git diff --exit-code
         displayName: AUTHORS file check
 
diff --git a/buildlib/tools/codestyle.sh b/buildlib/tools/codestyle.sh
index e07573c48fd..4b0bd29238c 100644
--- a/buildlib/tools/codestyle.sh
+++ b/buildlib/tools/codestyle.sh
@@ -8,10 +8,10 @@ codestyle_check_commit_title() {
     local range="$1"
     local err=0
 
-    for sha1 in `git log "$range" --format="%h"`
+    for sha1 in $(git log --first-parent --no-merges "$range" --format="%h")
     do
-        title=`git log -1 --format="%s" $sha1`
-        if echo $title | grep -qP '^Merge |^[0-9A-Z/_\-]*: \w'
+        title=$(git log -1 --format="%s" $sha1)
+        if [[ $title =~ ^[0-9A-Z/_-]*:\ [[:alnum:]_] ]]
         then
             echo "Good commit title: '$title'"
         else
diff --git a/contrib/authors_update.sh b/contrib/authors_update.sh
index a9e60a625c9..c25bc49f8a9 100755
--- a/contrib/authors_update.sh
+++ b/contrib/authors_update.sh
@@ -15,7 +15,8 @@ then
 fi
 
 # Failure message triggered if range is not valid
-lines=$(git log --no-merges --pretty=format:"%an%x09%ae" "$range" | sort -u)
+lines=$(git log --first-parent --no-merges --pretty=format:"%an%x09%ae" \
+            "$range" | sort -u)
 if [ -z "$lines" ]
 then
     echo "Error: provided range \"$range\" is empty"