diff --git a/spec/build/bsps/microblaze/microblaze_fpga/optconsoleuart.yml b/spec/build/bsps/microblaze/microblaze_fpga/optconsoleuart.yml
index 8cc8e18062..c183baed5c 100644
--- a/spec/build/bsps/microblaze/microblaze_fpga/optconsoleuart.yml
+++ b/spec/build/bsps/microblaze/microblaze_fpga/optconsoleuart.yml
@@ -11,7 +11,6 @@ copyrights:
 default:
 - enabled-by: true
   value: 0
-default-by-variant: []
 description: |
   default uart console device port number
 enabled-by: true
diff --git a/spec/build/bsps/microblaze/microblaze_fpga/optmaxuarts.yml b/spec/build/bsps/microblaze/microblaze_fpga/optmaxuarts.yml
index 3b639a5922..33a0602730 100644
--- a/spec/build/bsps/microblaze/microblaze_fpga/optmaxuarts.yml
+++ b/spec/build/bsps/microblaze/microblaze_fpga/optmaxuarts.yml
@@ -11,7 +11,6 @@ copyrights:
 default:
 - enabled-by: true
   value: 1
-default-by-variant: []
 description: |
   maximum number of UART devices
 enabled-by: true
diff --git a/spec/build/bsps/microblaze/microblaze_fpga/optuartirq.yml b/spec/build/bsps/microblaze/microblaze_fpga/optuartirq.yml
index 054388bf8a..3faf6e24e6 100644
--- a/spec/build/bsps/microblaze/microblaze_fpga/optuartirq.yml
+++ b/spec/build/bsps/microblaze/microblaze_fpga/optuartirq.yml
@@ -10,7 +10,6 @@ copyrights:
 default:
 - enabled-by: true
   value: 3
-default-by-variant: []
 description: |
   irq number of the AXI UART Lite
 enabled-by: true
diff --git a/spec/build/bsps/microblaze/microblaze_fpga/optuseuart.yml b/spec/build/bsps/microblaze/microblaze_fpga/optuseuart.yml
index c3ddd11b78..9136297ba8 100644
--- a/spec/build/bsps/microblaze/microblaze_fpga/optuseuart.yml
+++ b/spec/build/bsps/microblaze/microblaze_fpga/optuseuart.yml
@@ -8,7 +8,6 @@ copyrights:
 default:
 - enabled-by: true
   value: true
-default-by-variant: []
 description: |
   define if UART is used
 enabled-by: true