diff --git a/include/polarssl/ctr_drbg.h b/include/polarssl/ctr_drbg.h
index 4b5a444..bebbfe9 100644
--- a/include/polarssl/ctr_drbg.h
+++ b/include/polarssl/ctr_drbg.h
@@ -131,6 +131,13 @@
                    size_t len );
 
 /**
+ * \brief               Clear CTR_CRBG context data
+ *
+ * \param ctx           CTR_DRBG context to clear
+ */
+void ctr_drbg_free( ctr_drbg_context *ctx );
+
+/**
  * \brief               Enable / disable prediction resistance (Default: Off)
  *
  * Note: If enabled, entropy is used for ctx->entropy_len before each call!