diff --git a/library/ccm.c b/library/ccm.c
index 957fda9ea..109927e4c 100644
--- a/library/ccm.c
+++ b/library/ccm.c
@@ -74,10 +74,6 @@ int mbedtls_ccm_setkey( mbedtls_ccm_context *ctx,
     int ret;
     const mbedtls_cipher_info_t *cipher_info;
 
-    memset( ctx, 0, sizeof( mbedtls_ccm_context ) );
-
-    mbedtls_cipher_init( &ctx->cipher_ctx );
-
     cipher_info = mbedtls_cipher_info_from_values( cipher, keysize, MBEDTLS_MODE_ECB );
     if( cipher_info == NULL )
         return( MBEDTLS_ERR_CCM_BAD_INPUT );
diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index 54feb71c9..00b50d26b 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -82,7 +82,6 @@ int mbedtls_ctr_drbg_seed_entropy_len(
     int ret;
     unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE];
 
-    memset( ctx, 0, sizeof(mbedtls_ctr_drbg_context) );
     memset( key, 0, MBEDTLS_CTR_DRBG_KEYSIZE );
 
     mbedtls_aes_init( &ctx->aes_ctx );
diff --git a/library/gcm.c b/library/gcm.c
index 58cb4f283..39648b4c6 100644
--- a/library/gcm.c
+++ b/library/gcm.c
@@ -167,10 +167,6 @@ int mbedtls_gcm_setkey( mbedtls_gcm_context *ctx,
     int ret;
     const mbedtls_cipher_info_t *cipher_info;
 
-    memset( ctx, 0, sizeof(mbedtls_gcm_context) );
-
-    mbedtls_cipher_init( &ctx->cipher_ctx );
-
     cipher_info = mbedtls_cipher_info_from_values( cipher, keysize, MBEDTLS_MODE_ECB );
     if( cipher_info == NULL )
         return( MBEDTLS_ERR_GCM_BAD_INPUT );
diff --git a/library/hmac_drbg.c b/library/hmac_drbg.c
index 02fcc7d00..5c4ee6def 100644
--- a/library/hmac_drbg.c
+++ b/library/hmac_drbg.c
@@ -105,10 +105,6 @@ int mbedtls_hmac_drbg_seed_buf( mbedtls_hmac_drbg_context *ctx,
 {
     int ret;
 
-    memset( ctx, 0, sizeof( mbedtls_hmac_drbg_context ) );
-
-    mbedtls_md_init( &ctx->md_ctx );
-
     if( ( ret = mbedtls_md_setup( &ctx->md_ctx, md_info, 1 ) ) != 0 )
         return( ret );
 
@@ -179,10 +175,6 @@ int mbedtls_hmac_drbg_seed( mbedtls_hmac_drbg_context *ctx,
     int ret;
     size_t entropy_len, md_size;
 
-    memset( ctx, 0, sizeof( mbedtls_hmac_drbg_context ) );
-
-    mbedtls_md_init( &ctx->md_ctx );
-
     if( ( ret = mbedtls_md_setup( &ctx->md_ctx, md_info, 1 ) ) != 0 )
         return( ret );