diff --git a/library/pem.c b/library/pem.c
index 4c2337393c..f7051ecd27 100644
--- a/library/pem.c
+++ b/library/pem.c
@@ -331,7 +331,9 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
 
     if( ( ret = mbedtls_base64_decode( buf, len, &len, s1, s2 - s1 ) ) != 0 )
     {
+        mbedtls_zeroize( buf, len );
         mbedtls_free( buf );
+        buf = NULL;
         return( MBEDTLS_ERR_PEM_INVALID_DATA + ret );
     }
 
@@ -341,7 +343,9 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
     ( defined(MBEDTLS_DES_C) || defined(MBEDTLS_AES_C) )
         if( pwd == NULL )
         {
+            mbedtls_zeroize( buf, len );
             mbedtls_free( buf );
+            buf = NULL;
             return( MBEDTLS_ERR_PEM_PASSWORD_REQUIRED );
         }
 
@@ -369,7 +373,9 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
          */
         if( len <= 2 || buf[0] != 0x30 || buf[1] > 0x83 )
         {
+            mbedtls_zeroize( buf, len );
             mbedtls_free( buf );
+            buf = NULL;
             return( MBEDTLS_ERR_PEM_PASSWORD_MISMATCH );
         }
 #else
@@ -387,7 +393,8 @@ int mbedtls_pem_read_buffer( mbedtls_pem_context *ctx, const char *header, const
 
 void mbedtls_pem_free( mbedtls_pem_context *ctx )
 {
-    memset( ctx->buf, 0, ctx->buflen );
+    if( ctx->buf )
+        mbedtls_zeroize( ctx->buf, ctx->buflen );
     mbedtls_free( ctx->buf );
     mbedtls_free( ctx->info );