diff --git a/ChangeLog b/ChangeLog
index 1a85af29a0..a47cdebc33 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -13,6 +13,8 @@ Security
    * Tighten should-be-constant-time memcmp against compiler optimizations.
    * Ensure that buffers are cleared after use if they contain sensitive data.
      Changes were introduced in multiple places in the library.
+   * Set PEM buffer to zero before freeing it, to avoid decoded private keys
+     being leaked to memory after release.
 
 Bugfix
    * Fix memory leak in ssl_set_hostname() when called multiple times.
diff --git a/library/pem.c b/library/pem.c
index 789a92d511..fedbc5cbb1 100644
--- a/library/pem.c
+++ b/library/pem.c
@@ -393,6 +393,8 @@ int pem_read_buffer( pem_context *ctx, const char *header, const char *footer,
 
 void pem_free( pem_context *ctx )
 {
+    if ( ctx->buf != NULL )
+        polarssl_zeroize( ctx->buf, ctx->buflen );
     polarssl_free( ctx->buf );
     polarssl_free( ctx->info );