diff --git a/ChangeLog.d/psa_allow_tweaking_library_configuration.txt b/ChangeLog.d/psa_allow_tweaking_library_configuration.txt
new file mode 100644
index 000000000..3ab88d6e3
--- /dev/null
+++ b/ChangeLog.d/psa_allow_tweaking_library_configuration.txt
@@ -0,0 +1,5 @@
+Features
+   * The PSA crypto subsystem can now be configured to use less static RAM by
+     tweaking the setting for the maximum amount of keys simultaneously in RAM.
+     PSA_KEY_SLOT_COUNT sets the maximum number of volatile keys that can
+     exist simultaneously. It has a sensible default if not overridden.
diff --git a/library/psa_crypto_slot_management.h b/library/psa_crypto_slot_management.h
index ef0814ac9..32ccd4982 100644
--- a/library/psa_crypto_slot_management.h
+++ b/library/psa_crypto_slot_management.h
@@ -27,7 +27,9 @@
 
 /* Number of key slots (plus one because 0 is not used).
  * The value is a compile-time constant for now, for simplicity. */
+#if !defined(PSA_KEY_SLOT_COUNT)
 #define PSA_KEY_SLOT_COUNT 32
+#endif
 
 /** Range of volatile key identifiers.
  *