diff --git a/ros2caret/verb/record.py b/ros2caret/verb/record.py
index 8d718349..7a1f97c7 100644
--- a/ros2caret/verb/record.py
+++ b/ros2caret/verb/record.py
@@ -12,14 +12,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import math
 import os
 
 from typing import Optional
 
 from caret_msgs.msg import End, Start, Status
 
-import numpy as np
-
 import rclpy
 from rclpy import qos
 from rclpy.node import Node
@@ -191,7 +190,7 @@ def main(self, *, args):
                 and args.subbuffer_size_ust != 8*4096:
             raise ValueError('the --subbuffer-size-ust option is '
                              'available in iron or rolling')
-        if not np.log2(args.subbuffer_size_ust).is_integer():
+        if not math.log2(args.subbuffer_size_ust).is_integer():
             raise ValueError('--subbuffer-size-ust value must be power of two.')
         init_args['subbuffer_size_ust'] = args.subbuffer_size_ust
 
@@ -199,7 +198,7 @@ def main(self, *, args):
                 and args.subbuffer_size_kernel != 32*4096:
             raise ValueError('the --subbuffer-size-kernel option is '
                              'available in iron or rolling')
-        if not np.log2(args.subbuffer_size_kernel).is_integer():
+        if not math.log2(args.subbuffer_size_kernel).is_integer():
             raise ValueError('--subbuffer-size-kernel value must be power of two.')
         init_args['subbuffer_size_kernel'] = args.subbuffer_size_kernel
         init(**init_args)