diff --git a/core/http/Cargo.toml b/core/http/Cargo.toml
index a83b2c3aa5..1037a501d2 100644
--- a/core/http/Cargo.toml
+++ b/core/http/Cargo.toml
@@ -21,7 +21,7 @@ private-cookies = ["cookie/secure"]
 
 [dependencies]
 smallvec = "1.0"
-percent-encoding = "1"
+percent-encoding = "2"
 hyper = { version = "0.13.0", default-features = false }
 http = "0.2"
 mime = "0.3.13"
diff --git a/core/http/src/lib.rs b/core/http/src/lib.rs
index fe951fa40f..c28379ffa1 100644
--- a/core/http/src/lib.rs
+++ b/core/http/src/lib.rs
@@ -1,3 +1,5 @@
+#![feature(const_if_match)]
+#![feature(const_loop)]
 #![feature(proc_macro_hygiene)]
 #![recursion_limit="512"]
 
diff --git a/core/http/src/parse/uri/tables.rs b/core/http/src/parse/uri/tables.rs
index 7258e9e4a7..ad78cf6541 100644
--- a/core/http/src/parse/uri/tables.rs
+++ b/core/http/src/parse/uri/tables.rs
@@ -30,7 +30,7 @@ const PATH_CHARS: [u8; 256] = [
 ];
 
 #[inline(always)]
-pub fn is_pchar(c: u8) -> bool {
+pub const fn is_pchar(c: u8) -> bool {
     PATH_CHARS[c as usize] == c
 }
 
diff --git a/core/http/src/uri/encoding.rs b/core/http/src/uri/encoding.rs
index 3b989eb6c7..625afdd069 100644
--- a/core/http/src/uri/encoding.rs
+++ b/core/http/src/uri/encoding.rs
@@ -1,7 +1,7 @@
 use std::marker::PhantomData;
 use std::borrow::Cow;
 
-use percent_encoding::{EncodeSet, utf8_percent_encode};
+use percent_encoding::{AsciiSet, utf8_percent_encode};
 
 use crate::uri::{UriPart, Path, Query};
 use crate::parse::uri::is_pchar;
@@ -9,6 +9,25 @@ use crate::parse::uri::is_pchar;
 #[derive(Clone, Copy)]
 #[allow(non_camel_case_types)]
 pub struct UNSAFE_ENCODE_SET<P: UriPart>(PhantomData<P>);
+pub trait EncodeSet {
+    const SET: AsciiSet;
+}
+
+const fn build_set_from_table() -> AsciiSet {
+    const ASCII_RANGE_LEN: u8 = 0x80;
+
+    let mut set = percent_encoding::CONTROLS.remove(0);
+    let mut b: u8 = 0;
+    while b < ASCII_RANGE_LEN {
+        if !is_pchar(b) {
+            set = set.add(b);
+        }
+        b += 1;
+    }
+    set
+}
+
+const PATH_SET: AsciiSet = build_set_from_table();
 
 impl<P: UriPart> Default for UNSAFE_ENCODE_SET<P> {
     #[inline(always)]
@@ -16,17 +35,15 @@ impl<P: UriPart> Default for UNSAFE_ENCODE_SET<P> {
 }
 
 impl EncodeSet for UNSAFE_ENCODE_SET<Path> {
-    #[inline(always)]
-    fn contains(&self, byte: u8) -> bool {
-        !is_pchar(byte) || byte == b'%'
-    }
+    const SET: AsciiSet = PATH_SET
+        .add(b'%');
 }
 
 impl EncodeSet for UNSAFE_ENCODE_SET<Query> {
-    #[inline(always)]
-    fn contains(&self, byte: u8) -> bool {
-        (!is_pchar(byte) && (byte != b'?')) || byte == b'%' || byte == b'+'
-    }
+    const SET: AsciiSet = PATH_SET
+        .remove(b'?')
+        .add(b'%')
+        .add(b'+');
 }
 
 #[derive(Clone, Copy)]
@@ -34,20 +51,14 @@ impl EncodeSet for UNSAFE_ENCODE_SET<Query> {
 pub struct ENCODE_SET<P: UriPart>(PhantomData<P>);
 
 impl EncodeSet for ENCODE_SET<Path> {
-    #[inline(always)]
-    fn contains(&self, byte: u8) -> bool {
-        <UNSAFE_ENCODE_SET<Path>>::default().contains(byte) || byte == b'/'
-    }
+    const SET: AsciiSet = <UNSAFE_ENCODE_SET<Path>>::SET
+        .add(b'/');
 }
 
 impl EncodeSet for ENCODE_SET<Query> {
-    #[inline(always)]
-    fn contains(&self, byte: u8) -> bool {
-        <UNSAFE_ENCODE_SET<Query>>::default().contains(byte) || match byte {
-            b'&' | b'=' => true,
-            _ => false
-        }
-    }
+    const SET: AsciiSet = <UNSAFE_ENCODE_SET<Query>>::SET
+        .add(b'&')
+        .add(b'=');
 }
 
 #[derive(Default, Clone, Copy)]
@@ -55,11 +66,11 @@ impl EncodeSet for ENCODE_SET<Query> {
 pub struct DEFAULT_ENCODE_SET;
 
 impl EncodeSet for DEFAULT_ENCODE_SET {
-    #[inline(always)]
-    fn contains(&self, byte: u8) -> bool {
-        ENCODE_SET::<Path>(PhantomData).contains(byte) ||
-            ENCODE_SET::<Query>(PhantomData).contains(byte)
-    }
+    const SET: AsciiSet = <ENCODE_SET<Path>>::SET
+        .add(b'%')
+        .add(b'+')
+        .add(b'&')
+        .add(b'=');
 }
 
 pub fn unsafe_percent_encode<P: UriPart>(string: &str) -> Cow<'_, str> {
@@ -71,5 +82,5 @@ pub fn unsafe_percent_encode<P: UriPart>(string: &str) -> Cow<'_, str> {
 }
 
 pub fn percent_encode<S: EncodeSet + Default>(string: &str) -> Cow<'_, str> {
-    utf8_percent_encode(string, S::default()).into()
+    utf8_percent_encode(string, &S::SET).into()
 }
diff --git a/core/lib/Cargo.toml b/core/lib/Cargo.toml
index 5c7a29bc05..f316510259 100644
--- a/core/lib/Cargo.toml
+++ b/core/lib/Cargo.toml
@@ -36,7 +36,7 @@ num_cpus = "1.0"
 state = "0.4.1"
 time = "0.1"
 memchr = "2" # TODO: Use pear instead.
-base64 = "0.11"
+base64 = "0.12"
 base16 = "0.2"
 pear = "0.1"
 atty = "0.2"