diff --git a/core/fxcrt/widestring.cpp b/core/fxcrt/widestring.cpp
index b38503f..8d037b0 100644
--- a/core/fxcrt/widestring.cpp
+++ b/core/fxcrt/widestring.cpp
@@ -10,6 +10,7 @@
 #include <string.h>
 
 #include <algorithm>
+#include <ostream>
 
 #include "core/fxcrt/fx_codepage.h"
 #include "core/fxcrt/fx_extension.h"
diff --git a/third_party/BUILD.gn b/third_party/BUILD.gn
index 5e8a2c1..5128631 100644
--- a/third_party/BUILD.gn
+++ b/third_party/BUILD.gn
@@ -560,12 +560,19 @@
   }
 }
 
+config("pdfium_base_config") {
+  defines = [ "BASE_NUMERICS_DISABLE_OSTREAM_OPERATORS" ]
+}
+
 source_set("pdfium_base") {
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [
     "//build/config/compiler:no_chromium_code",
     ":pdfium_third_party_config",
   ]
+
+  public_configs = [ ":pdfium_base_config" ]
+
   sources = [
     "base/allocator/partition_allocator/address_space_randomization.cc",
     "base/allocator/partition_allocator/address_space_randomization.h",