diff --git a/auglib/core/transform.py b/auglib/core/transform.py
index 7387129..562882a 100644
--- a/auglib/core/transform.py
+++ b/auglib/core/transform.py
@@ -2056,6 +2056,10 @@ def _call(
 
         signal = self.function(signal, sampling_rate, **args)
 
+        # Ensure signal is not read-only
+        if not signal.flags["WRITEABLE"]:
+            signal = signal.copy()
+
         return signal