diff --git a/src/http/modules/ngx_http_autoindex_module.c b/src/http/modules/ngx_http_autoindex_module.c
index 221455120..f694df075 100644
--- a/src/http/modules/ngx_http_autoindex_module.c
+++ b/src/http/modules/ngx_http_autoindex_module.c
@@ -233,6 +233,7 @@ ngx_http_autoindex_handler(ngx_http_request_t *r)
     r->headers_out.status = NGX_HTTP_OK;
     r->headers_out.content_type_len = sizeof("text/html") - 1;
     ngx_str_set(&r->headers_out.content_type, "text/html");
+    r->headers_out.content_type_lowcase = NULL;
 
     rc = ngx_http_send_header(r);
 
diff --git a/src/http/modules/ngx_http_image_filter_module.c b/src/http/modules/ngx_http_image_filter_module.c
index cc41ef0d5..c983b973b 100644
--- a/src/http/modules/ngx_http_image_filter_module.c
+++ b/src/http/modules/ngx_http_image_filter_module.c
@@ -572,6 +572,7 @@ ngx_http_image_json(ngx_http_request_t *r, ngx_http_image_filter_ctx_t *ctx)
     ngx_http_clean_header(r);
 
     r->headers_out.status = NGX_HTTP_OK;
+    r->headers_out.content_type_len = sizeof("application/json") - 1;
     ngx_str_set(&r->headers_out.content_type, "application/json");
     r->headers_out.content_type_lowcase = NULL;
 
diff --git a/src/http/modules/ngx_http_stub_status_module.c b/src/http/modules/ngx_http_stub_status_module.c
index fe9132df8..b5ecd6d9e 100644
--- a/src/http/modules/ngx_http_stub_status_module.c
+++ b/src/http/modules/ngx_http_stub_status_module.c
@@ -98,7 +98,9 @@ static ngx_int_t ngx_http_status_handler(ngx_http_request_t *r)
         return rc;
     }
 
+    r->headers_out.content_type_len = sizeof("text/plain") - 1;
     ngx_str_set(&r->headers_out.content_type, "text/plain");
+    r->headers_out.content_type_lowcase = NULL;
 
     if (r->method == NGX_HTTP_HEAD) {
         r->headers_out.status = NGX_HTTP_OK;