diff --git a/kissat/Cargo.toml b/kissat/Cargo.toml
index 9246222b..b5388177 100644
--- a/kissat/Cargo.toml
+++ b/kissat/Cargo.toml
@@ -17,6 +17,7 @@ build = "build.rs"
 debug = []
 safe = []
 quiet = []
+v4-0-0 = []
 v3-1-1 = []
 v3-1-0 = []
 v3-0-0 = []
diff --git a/kissat/README.md b/kissat/README.md
index cfa4e388..5fd04177 100644
--- a/kissat/README.md
+++ b/kissat/README.md
@@ -21,6 +21,7 @@ Armin Biere's SAT solver [Kissat](https://github.com/arminbiere/kissat) to be us
 
 Kissat versions can be selected via cargo crate features.
 The following Kissat versions are available:
+- `v4-0-0`: [Version 4.0.0](https://github.com/arminbiere/kissat/releases/tag/rel-4.0.0)
 - `v3-1-0`: [Version 3.1.0](https://github.com/arminbiere/kissat/releases/tag/rel-3.1.0)
 - `v3-0-0`: [Version 3.0.0](https://github.com/arminbiere/kissat/releases/tag/rel-3.0.0)
 - `sc2022-light`: [SAT Competition 2022 Light](https://github.com/arminbiere/kissat/releases/tag/sc2022-light)
diff --git a/kissat/build-all.sh b/kissat/build-all.sh
index 104fcf6d..7444b863 100755
--- a/kissat/build-all.sh
+++ b/kissat/build-all.sh
@@ -35,6 +35,11 @@ if [ "$1" == "--clean" ]; then cargo clean -p rustsat-kissat > /dev/null; fi
 cargo build --features=v3-1-1 &> v311-build.log
 echo "v3.1.1 build returned: $?"
 
+echo "Building v4.0.0"
+if [ "$1" == "--clean" ]; then cargo clean -p rustsat-kissat > /dev/null; fi
+cargo build --features=v4-0-0 &> v400-build.log
+echo "v4.0.0 build returned: $?"
+
 echo "Building quiet"
 if [ "$1" == "--clean" ]; then cargo clean -p rustsat-kissat > /dev/null; fi
 cargo build --features=quiet &> quiet-build.log
diff --git a/kissat/build.rs b/kissat/build.rs
index 9b63c231..18b7b60d 100644
--- a/kissat/build.rs
+++ b/kissat/build.rs
@@ -17,7 +17,9 @@ fn main() {
     }
 
     // Select commit based on features. If conflict, always choose newest release
-    let tag = if cfg!(feature = "v3-1-1") {
+    let tag = if cfg!(feature = "v4-0-0") {
+        "refs/tags/rel-4.0.0"
+    } else if cfg!(feature = "v3-1-1") {
         "refs/tags/rel-3.1.1"
     } else if cfg!(feature = "v3-1-0") {
         "refs/tags/rel-3.1.0"
@@ -31,7 +33,7 @@ fn main() {
         "refs/tags/sc2022-bulky"
     } else {
         // default to newest version
-        "refs/tags/rel-3.1.1"
+        "refs/tags/rel-4.0.0"
     };
 
     // Build C library
diff --git a/kissat/src/lib.rs b/kissat/src/lib.rs
index 14cfde90..08d2bbbe 100644
--- a/kissat/src/lib.rs
+++ b/kissat/src/lib.rs
@@ -14,6 +14,7 @@
 //!
 //! Kissat versions can be selected via cargo crate features.
 //! The following Kissat versions are available:
+//! - `v4-0-0`: [Version 4.0.0](https://github.com/arminbiere/kissat/releases/tag/rel-4.0.0)
 //! - `v3-1-0`: [Version 3.1.0](https://github.com/arminbiere/kissat/releases/tag/rel-3.1.0)
 //! - `v3-0-0`: [Version 3.0.0](https://github.com/arminbiere/kissat/releases/tag/rel-3.0.0)
 //! - `sc2022-light`: [SAT Competition 2022 Light](https://github.com/arminbiere/kissat/releases/tag/sc2022-light)
diff --git a/kissat/test-all.sh b/kissat/test-all.sh
index 473d2789..97d2a5ff 100755
--- a/kissat/test-all.sh
+++ b/kissat/test-all.sh
@@ -28,6 +28,10 @@ echo "Testing v3.1.1"
 cargo test --features=v3-1-1 &> v311-test.log
 echo "v3.1.1 test returned: $?"
 
+echo "Testing v4.0.0"
+cargo test --features=v4-0-0 &> v400-test.log
+echo "v4.0.0 test returned: $?"
+
 echo "Testing quiet"
 cargo test --features=quiet &> quiet-test.log
 echo "quiet test returned: $?"