diff --git a/include/psa/crypto.h b/include/psa/crypto.h
index 515e65f3d..8059ab9e2 100644
--- a/include/psa/crypto.h
+++ b/include/psa/crypto.h
@@ -3122,6 +3122,15 @@ psa_status_t psa_generator_import_key(psa_key_slot_t key,
  */
 psa_status_t psa_generator_abort(psa_crypto_generator_t *generator);
 
+/** Use the maximum possible capacity for a generator.
+ *
+ * Use this value as the capacity argument when setting up a generator
+ * to indicate that the generator should have the maximum possible capacity.
+ * The value of the maximum possible capacity depends on the generator
+ * algorithm.
+ */
+#define PSA_GENERATOR_UNBRIDLED_CAPACITY ((size_t)(-1))
+
 /**@}*/
 
 /** \defgroup derivation Key derivation
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 202552391..3c1cec930 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -3539,6 +3539,8 @@ static psa_status_t psa_key_derivation_internal(
 
     if( capacity <= max_capacity )
         generator->capacity = capacity;
+    else if( capacity == PSA_GENERATOR_UNBRIDLED_CAPACITY )
+        generator->capacity = max_capacity;
     else
         return( PSA_ERROR_INVALID_ARGUMENT );