diff --git a/ChangeLog.d/use_exp_mod_core.txt b/ChangeLog.d/use_exp_mod_core.txt
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+Changes
+   * Changed the default MBEDTLS_ECP_WINDOW_SIZE from 2 to 3.
+     The correlation between this define and RSA decryption performance has
+     changed lately due to security hardening.
+     To fix the performance degradation when using default values the
+     window was increased from 2 to 3.