diff --git a/deps/base64/base64/lib/env.h b/deps/base64/base64/lib/env.h
index d5c2fdb7952735..024b46d1f716d7 100644
--- a/deps/base64/base64/lib/env.h
+++ b/deps/base64/base64/lib/env.h
@@ -46,12 +46,12 @@
 #if defined (__x86_64__)
 // This also works for the x32 ABI, which has a 64-bit word size.
 #  define BASE64_WORDSIZE 64
-#elif defined (_INTEGRAL_MAX_BITS)
-#  define BASE64_WORDSIZE _INTEGRAL_MAX_BITS
 #elif defined (__WORDSIZE)
 #  define BASE64_WORDSIZE __WORDSIZE
 #elif defined (__SIZE_WIDTH__)
 #  define BASE64_WORDSIZE __SIZE_WIDTH__
+#elif defined (_INTEGRAL_MAX_BITS) && !defined(_WIN32)
+#  define BASE64_WORDSIZE _INTEGRAL_MAX_BITS
 #else
 #  error BASE64_WORDSIZE_NOT_DEFINED
 #endif
diff --git a/deps/base64/unofficial.gni b/deps/base64/unofficial.gni
index 8138d88798e1df..269c62d976d6ad 100644
--- a/deps/base64/unofficial.gni
+++ b/deps/base64/unofficial.gni
@@ -32,6 +32,7 @@ template("base64_gn_build") {
         "HAVE_SSE42=1",
         "HAVE_AVX=1",
         "HAVE_AVX2=1",
+        "HAVE_AVX512=1",
       ]
     }
     if (target_cpu == "arm") {
@@ -65,6 +66,7 @@ template("base64_gn_build") {
       ":base64_sse42",
       ":base64_avx",
       ":base64_avx2",
+      ":base64_avx512",
       ":base64_neon32",
       ":base64_neon64",
     ]
@@ -111,6 +113,7 @@ template("base64_gn_build") {
       }
     }
   }
+
   source_set("base64_avx2") {
     configs += [ ":base64_internal_config" ]
     sources = [ "base64/lib/arch/avx2/codec.c" ]
@@ -123,6 +126,21 @@ template("base64_gn_build") {
     }
   }
 
+  source_set("base64_avx512") {
+    configs += [ ":base64_internal_config" ]
+    sources = [ "base64/lib/arch/avx512/codec.c" ]
+    if (target_cpu == "x86" || target_cpu == "x64") {
+      if (is_clang || !is_win) {
+        cflags_c = [
+          "-mavx512vl",
+          "-mavx512vbmi",
+        ]
+      } else if (is_win) {
+        cflags_c = [ "/arch:AVX512" ]
+      }
+    }
+  }
+
   source_set("base64_neon32") {
     configs += [ ":base64_internal_config" ]
     sources = [ "base64/lib/arch/neon32/codec.c" ]