diff --git a/tools/pickman/control.py b/tools/pickman/control.py
index e6b7539ea34..892100f3479 100644
--- a/tools/pickman/control.py
+++ b/tools/pickman/control.py
@@ -151,7 +151,7 @@ def get_next_commits(dbs, source):
     """Get the next set of commits to cherry-pick from a source
 
     Finds commits between the last cherry-picked commit and the next merge
-    commit in the source branch.
+    commit on the first-parent (mainline) chain of the source branch.
 
     Args:
         dbs (Database): Database instance
@@ -169,20 +169,38 @@ def get_next_commits(dbs, source):
     if not last_commit:
         return None, False, f"Source '{source}' not found in database"
 
-    # Get commits between last_commit and source HEAD (oldest first)
-    # Format: hash|short_hash|author|subject|parents
-    # Using | as separator since subject may contain colons
+    # First, find the next merge commit on the first-parent chain
+    # This ensures we follow the mainline and find merges in order
+    fp_output = run_git([
+        'log', '--reverse', '--first-parent', '--format=%H|%h|%an|%s|%P',
+        f'{last_commit}..{source}'
+    ])
+
+    if not fp_output:
+        return [], False, None
+
+    # Find the first merge on the first-parent chain
+    merge_hash = None
+    for line in fp_output.split('\n'):
+        if not line:
+            continue
+        parts = line.split('|')
+        parents = parts[-1].split()
+        if len(parents) > 1:
+            merge_hash = parts[0]
+            break
+
+    # Now get all commits from last_commit to the merge (or end of branch)
+    # Without --first-parent to include commits from merged branches
     log_output = run_git([
         'log', '--reverse', '--format=%H|%h|%an|%s|%P',
-        f'{last_commit}..{source}'
+        f'{last_commit}..{merge_hash or source}'
     ])
 
     if not log_output:
         return [], False, None
 
     commits = []
-    merge_found = False
-
     for line in log_output.split('\n'):
         if not line:
             continue
@@ -191,16 +209,10 @@ def get_next_commits(dbs, source):
         short_hash = parts[1]
         author = parts[2]
         subject = '|'.join(parts[3:-1])  # Subject may contain separator
-        parents = parts[-1].split()
 
         commits.append(CommitInfo(commit_hash, short_hash, subject, author))
 
-        # Check if this is a merge commit (has multiple parents)
-        if len(parents) > 1:
-            merge_found = True
-            break
-
-    return commits, merge_found, None
+    return commits, bool(merge_hash), None
 
 
 def do_next_set(args, dbs):
diff --git a/tools/pickman/ftest.py b/tools/pickman/ftest.py
index 80aa73f8a5b..784e8dd5d1b 100644
--- a/tools/pickman/ftest.py
+++ b/tools/pickman/ftest.py
@@ -840,14 +840,27 @@ class TestNextSet(unittest.TestCase):
 
         database.Database.instances.clear()
 
-        # Mock git log with commits including a merge
-        log_output = (
+        # First-parent log (to find next merge on mainline)
+        fp_log_output = (
             'aaa111|aaa111a|Author 1|First commit|abc123\n'
             'bbb222|bbb222b|Author 2|Second commit|aaa111\n'
             'ccc333|ccc333c|Author 3|Merge branch feature|bbb222 ddd444\n'
             'eee555|eee555e|Author 4|After merge|ccc333\n'
         )
-        command.TEST_RESULT = command.CommandResult(stdout=log_output)
+        # Full log (to get all commits up to the merge)
+        full_log_output = (
+            'aaa111|aaa111a|Author 1|First commit|abc123\n'
+            'bbb222|bbb222b|Author 2|Second commit|aaa111\n'
+            'ccc333|ccc333c|Author 3|Merge branch feature|bbb222 ddd444\n'
+        )
+
+        def mock_git(pipe_list):
+            cmd = pipe_list[0] if pipe_list else []
+            if '--first-parent' in cmd:
+                return command.CommandResult(stdout=fp_log_output)
+            return command.CommandResult(stdout=full_log_output)
+
+        command.TEST_RESULT = mock_git
 
         args = argparse.Namespace(cmd='next-set', source='us/next')
         with terminal.capture() as (stdout, _):
@@ -931,11 +944,25 @@ class TestGetNextCommits(unittest.TestCase):
             dbs.source_set('us/next', 'abc123')
             dbs.commit()
 
-            log_output = (
+            # First-parent log (to find next merge on mainline)
+            fp_log_output = (
+                'aaa111|aaa111a|Author 1|First commit|abc123\n'
+                'bbb222|bbb222b|Author 2|Merge branch|aaa111 ccc333\n'
+                'ddd444|ddd444d|Author 3|After merge|bbb222\n'
+            )
+            # Full log (to get all commits up to the merge)
+            full_log_output = (
                 'aaa111|aaa111a|Author 1|First commit|abc123\n'
                 'bbb222|bbb222b|Author 2|Merge branch|aaa111 ccc333\n'
             )
-            command.TEST_RESULT = command.CommandResult(stdout=log_output)
+
+            def mock_git(pipe_list):
+                cmd = pipe_list[0] if pipe_list else []
+                if '--first-parent' in cmd:
+                    return command.CommandResult(stdout=fp_log_output)
+                return command.CommandResult(stdout=full_log_output)
+
+            command.TEST_RESULT = mock_git
 
             commits, merge_found, error = control.get_next_commits(dbs,
                                                                    'us/next')