diff --git a/programs/pkey/pk_encrypt.c b/programs/pkey/pk_encrypt.c
index ad00573..2eb139c 100644
--- a/programs/pkey/pk_encrypt.c
+++ b/programs/pkey/pk_encrypt.c
@@ -140,6 +140,7 @@
     printf( "\n  . Done (created \"%s\")\n\n", "result-enc.txt" );
 
 exit:
+    ctr_drbg_free( &ctr_drbg );
     entropy_free( &entropy );
 
 #if defined(POLARSSL_ERROR_C)