diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index 184e09f..bc5cc8f 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -86,11 +86,17 @@
 {
     memset( ctx, 0, sizeof( mbedtls_ctr_drbg_context ) );
 
+    ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
+
 #if defined(MBEDTLS_THREADING_C)
     mbedtls_mutex_init( &ctx->mutex );
 #endif
 }
 
+/*
+ *  This function resets CTR_DRBG context to the state immediately
+ *  after initial call of mbedtls_ctr_drbg_init().
+ */
 void mbedtls_ctr_drbg_free( mbedtls_ctr_drbg_context *ctx )
 {
     if( ctx == NULL )
@@ -101,6 +107,10 @@
 #endif
     mbedtls_aes_free( &ctx->aes_ctx );
     mbedtls_zeroize( ctx, sizeof( mbedtls_ctr_drbg_context ) );
+    ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
+#if defined(MBEDTLS_THREADING_C)
+    mbedtls_mutex_init( &ctx->mutex );
+#endif
 }
 
 void mbedtls_ctr_drbg_set_prediction_resistance( mbedtls_ctr_drbg_context *ctx, int resistance )
@@ -379,7 +389,6 @@
 
     if( ctx->entropy_len == 0 )
         ctx->entropy_len = MBEDTLS_CTR_DRBG_ENTROPY_LEN;
-    ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
 
     /*
      * Initialize with an empty key
diff --git a/library/hmac_drbg.c b/library/hmac_drbg.c
index f24a66c..26b15e9 100644
--- a/library/hmac_drbg.c
+++ b/library/hmac_drbg.c
@@ -87,6 +87,8 @@
 {
     memset( ctx, 0, sizeof( mbedtls_hmac_drbg_context ) );
 
+    ctx->reseed_interval = MBEDTLS_HMAC_DRBG_RESEED_INTERVAL;
+
 #if defined(MBEDTLS_THREADING_C)
     mbedtls_mutex_init( &ctx->mutex );
 #endif
@@ -298,8 +300,6 @@
     ctx->f_entropy = f_entropy;
     ctx->p_entropy = p_entropy;
 
-    ctx->reseed_interval = MBEDTLS_HMAC_DRBG_RESEED_INTERVAL;
-
     if( ctx->entropy_len == 0 )
     {
         /*
@@ -444,7 +444,8 @@
 }
 
 /*
- * Free an HMAC_DRBG context
+ *  This function resets HMAC_DRBG context to the state immediately
+ *  after initial call of mbedtls_hmac_drbg_init().
  */
 void mbedtls_hmac_drbg_free( mbedtls_hmac_drbg_context *ctx )
 {
@@ -456,6 +457,10 @@
 #endif
     mbedtls_md_free( &ctx->md_ctx );
     mbedtls_zeroize( ctx, sizeof( mbedtls_hmac_drbg_context ) );
+    ctx->reseed_interval = MBEDTLS_HMAC_DRBG_RESEED_INTERVAL;
+#if defined(MBEDTLS_THREADING_C)
+    mbedtls_mutex_init( &ctx->mutex );
+#endif
 }
 
 #if defined(MBEDTLS_FS_IO)