diff --git a/tools/buildman/builder.py b/tools/buildman/builder.py
index 7cbb1a6f628..e895ab73d8d 100644
--- a/tools/buildman/builder.py
+++ b/tools/buildman/builder.py
@@ -1253,7 +1253,7 @@ class Builder:
                 for line in err_lines:
                     boards = ''
                     names = [board.target for board in line.boards]
-                    board_str = ','.join(names) if names else ''
+                    board_str = ' '.join(names) if names else ''
                     if board_str:
                         out = self.col.Color(colour, line.char + '(')
                         out += self.col.Color(self.col.MAGENTA, board_str,
diff --git a/tools/buildman/test.py b/tools/buildman/test.py
index a64372dee36..a495df03036 100644
--- a/tools/buildman/test.py
+++ b/tools/buildman/test.py
@@ -249,9 +249,9 @@ class TestBuild(unittest.TestCase):
                 new_lines.append(expect)
             return '\n'.join(new_lines)
 
-        boards1234 = 'board1,board2,board3,board4' if list_error_boards else ''
-        boards234 = 'board2,board3,board4' if list_error_boards else ''
-        boards34 = 'board3,board4' if list_error_boards else ''
+        boards1234 = 'board1 board2 board3 board4' if list_error_boards else ''
+        boards234 = 'board2 board3 board4' if list_error_boards else ''
+        boards34 = 'board3 board4' if list_error_boards else ''
         boards4 = 'board4' if list_error_boards else ''
 
         # Upstream commit: no errors