diff --git a/Cargo.toml b/Cargo.toml
index 287572b..1c08d54 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -14,7 +14,7 @@ autoexamples = false # Remove when edition 2018 https://github.com/rust-lang/car
 
 # Should make docs.rs show all functions, even those behind non-default features
 [package.metadata.docs.rs]
-features = [ "rand", "rand-std", "serde", "recovery", "endomorphism" ]
+features = [ "rand", "rand-std", "serde", "recovery" ]
 
 [features]
 unstable = ["recovery", "rand-std"]
@@ -22,12 +22,11 @@ default = ["std"]
 std = ["secp256k1-sys/std"]
 rand-std = ["rand/std"]
 recovery = ["secp256k1-sys/recovery"]
-endomorphism = ["secp256k1-sys/endomorphism"]
 lowmemory = ["secp256k1-sys/lowmemory"]
 global-context = ["std", "rand-std"]
 
 [dependencies]
-secp256k1-sys = { version = "0.3.1", default-features = false, path = "./secp256k1-sys" }
+secp256k1-sys = { version = "0.4.0", default-features = false, path = "./secp256k1-sys" }
 bitcoin_hashes = { version = "0.9", optional = true }
 rand = { version = "0.6", default-features = false, optional = true }
 serde = { version = "1.0", default-features = false, optional = true }
diff --git a/contrib/test.sh b/contrib/test.sh
index dd8430e..17b4115 100755
--- a/contrib/test.sh
+++ b/contrib/test.sh
@@ -1,6 +1,6 @@
 #!/bin/sh -ex
 
-FEATURES="bitcoin_hashes endomorphism global-context lowmemory rand rand-std recovery serde"
+FEATURES="bitcoin_hashes global-context lowmemory rand rand-std recovery serde"
 
 # Use toolchain if explicitly specified
 if [ -n "$TOOLCHAIN" ]
diff --git a/no_std_test/src/main.rs b/no_std_test/src/main.rs
index 58e5c9c..0c49d06 100644
--- a/no_std_test/src/main.rs
+++ b/no_std_test/src/main.rs
@@ -83,7 +83,7 @@ impl RngCore for FakeRng {
 
 #[start]
 fn start(_argc: isize, _argv: *const *const u8) -> isize {
-    let mut buf = [AlignedType::zeroed(); 37_000];
+    let mut buf = [AlignedType::zeroed(); 70_000];
     let size = Secp256k1::preallocate_size();
     unsafe { libc::printf("needed size: %d\n\0".as_ptr() as _, size) };
 
diff --git a/secp256k1-sys/Cargo.toml b/secp256k1-sys/Cargo.toml
index 79e39e0..c602e80 100644
--- a/secp256k1-sys/Cargo.toml
+++ b/secp256k1-sys/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "secp256k1-sys"
-version = "0.3.1"
+version = "0.4.0"
 authors = [ "Dawid Ciężarkiewicz <dpc@ucore.info>",
             "Andrew Poelstra <apoelstra@wpsoftware.net>",
             "Steven Roose <steven@stevenroose.org>" ]
@@ -16,7 +16,7 @@ links = "rustsecp256k1_v0_4_0"
 
 # Should make docs.rs show all functions, even those behind non-default features
 [package.metadata.docs.rs]
-features = [ "recovery", "endomorphism", "lowmemory" ]
+features = [ "recovery", "lowmemory" ]
 
 [build-dependencies]
 cc = "1.0.28"
@@ -27,7 +27,6 @@ libc = "0.2"
 [features]
 default = ["std"]
 recovery = []
-endomorphism = []
 lowmemory = []
 std = []
 
diff --git a/secp256k1-sys/build.rs b/secp256k1-sys/build.rs
index 434dcad..4e28002 100644
--- a/secp256k1-sys/build.rs
+++ b/secp256k1-sys/build.rs
@@ -48,8 +48,6 @@ fn main() {
         base_config.define("ECMULT_WINDOW_SIZE", Some("15")); // This is the default in the configure file (`auto`)
     }
     base_config.define("USE_EXTERNAL_DEFAULT_CALLBACKS", Some("1"));
-    #[cfg(feature = "endomorphism")]
-    base_config.define("USE_ENDOMORPHISM", Some("1"));
     #[cfg(feature = "recovery")]
     base_config.define("ENABLE_MODULE_RECOVERY", Some("1"));