diff --git a/Cargo.toml b/Cargo.toml
index a9ebd1b..31803d8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,3 +16,6 @@ bindgen = "0.69"
 fs_extra = "1.0"
 pkg-config = "0.3"
 walkdir = "2.3"
+
+[features]
+patch-twi-inconsistencies = []
diff --git a/README.md b/README.md
index e455eec..367af89 100644
--- a/README.md
+++ b/README.md
@@ -3,15 +3,21 @@
 [crates-badge]: https://img.shields.io/crates/v/simavr-ffi.svg
 [crates-link]: https://crates.io/crates/simavr-ffi
 
-Low-level bindings to [simavr](https://github.com/buserror/simavr).
+Low-level bindings to [simavr](https://github.com/buserror/simavr):
 
-Supported platforms: Linux & Mac (pull requests for Windows welcome!).
+```toml
+[dependencies]
+simavr-ffi = "1.0.1"
+```
+
+Supported platforms: Linux & Mac (pull requests welcome!).
 
 ## Requirements
 
 Compile-time:
 
 - clang,
+- git,
 - libelf,
 - pkg-config,
 - zlib.
@@ -34,6 +40,12 @@ $ sudo apt install clang libelf-dev pkg-config
 $ brew install libelf pkg-config
 ```
 
+## Feature flags
+
+All feature flags are disabled by default - if you want, you can activate:
+
+- `patch-twi-inconsistencies` - applies a fix for https://github.com/buserror/simavr/issues/453
+
 ## FAQ
 
 ### How does it compare to `simavr-sys`?
diff --git a/build.rs b/build.rs
index 509aadf..353107d 100644
--- a/build.rs
+++ b/build.rs
@@ -9,40 +9,90 @@ use walkdir::WalkDir;
 fn main() {
     println!("cargo:rerun-if-changed=build.rs");
 
-    let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());
-
-    build_simavr(&out_path);
-    generate_simavr_bindings(&out_path);
-    link_libelf();
-    link_zlib();
-    link_libzstd();
+    let out = PathBuf::from(env::var("OUT_DIR").unwrap());
+
+    check();
+    patch();
+    copy(&out);
+    revert_patch();
+    build(&out);
+    generate_bindings(&out);
+    link();
 }
 
-fn build_simavr(out: &Path) {
-    println!("=> Building simavr");
-
+fn check() {
     if !Path::new("vendor")
         .join("simavr")
         .join("README.md")
         .exists()
     {
         panic!(
-            "\
-            `vendor/simavr` doesn't seem to contain the expected source code. \
-            If you're cloning simavr-ffi by hand, please use `git clone ... \
-            --recurse-submodules`."
+            "`vendor/simavr` doesn't exist - if you're cloning simavr-ffi by \
+             hand, please use `git clone ... --recurse-submodules`"
         );
     }
+}
+
+fn patch() {
+    println!("=> Patching simavr");
+
+    simavr_git(&["reset", "--hard", "HEAD"]);
+
+    #[cfg(feature = "patch-twi-inconsistencies")]
+    patch_ex("twi-inconsistencies.patch");
+}
+
+#[allow(unused)]
+fn patch_ex(name: &str) {
+    let path = Path::new(file!())
+        .parent()
+        .unwrap()
+        .join("patches")
+        .join(name)
+        .canonicalize()
+        .unwrap();
+
+    simavr_git(&["apply", &path.display().to_string()]);
+}
+
+fn copy(out: &Path) {
+    println!("=> Copying simavr");
+
+    let out_simavr = out.join("simavr");
+
+    if !out_simavr.exists() {
+        fs::create_dir(&out_simavr)
+            .with_context(|| format!("Couldn't create directory: {}", out_simavr.display()))
+            .unwrap();
+
+        fs_extra::copy_items(&["vendor/simavr"], &out_simavr, &Default::default())
+            .with_context(|| {
+                format!(
+                    "Couldn't copy simavr's sources to: {}",
+                    out_simavr.display()
+                )
+            })
+            .unwrap();
+    }
+}
+
+fn revert_patch() {
+    // Don't leave the tree dirty during development
+    simavr_git(&["reset", "--hard", "HEAD"]);
+}
+
+fn build(out: &Path) {
+    println!("=> Building simavr");
 
     #[cfg(target_family = "unix")]
-    build_simavr_unix(out);
+    build_unix(out);
 
     #[cfg(not(target_family = "unix"))]
-    panic!("Sorry, I don't know how to build simavr on this architecture");
+    panic!("simavr-ffi works only on Unixes right now - pull requests are welcome!");
 }
 
 #[cfg(target_family = "unix")]
-fn build_simavr_unix(out: &Path) {
+fn build_unix(out: &Path) {
     let out_simavr = out.join("simavr");
 
     if !out_simavr.exists() {
@@ -76,7 +126,7 @@ fn build_simavr_unix(out: &Path) {
     println!("cargo:rustc-link-lib=static=simavr");
 }
 
-fn generate_simavr_bindings(out: &Path) {
+fn generate_bindings(out: &Path) {
     println!("=> Generating simavr bindings");
 
     let mut builder = bindgen::Builder::default();
@@ -97,7 +147,6 @@ fn generate_simavr_bindings(out: &Path) {
         .map(|header| header.path().to_string_lossy().to_string());
 
     for header in headers {
-        println!("-> Found header: {}", header);
         builder = builder.header(header);
     }
 
@@ -110,6 +159,12 @@ fn generate_simavr_bindings(out: &Path) {
         .expect("Couldn't write simavr's bindings");
 }
 
+fn link() {
+    link_libelf();
+    link_zlib();
+    link_libzstd();
+}
+
 fn link_libelf() {
     println!("=> Linking libelf");
 
@@ -133,3 +188,21 @@ fn link_libzstd() {
 
     println!("cargo-rustc-link-lib=zstd");
 }
+
+fn simavr_git(args: &[&str]) {
+    let status = Command::new("git")
+        .current_dir("vendor/simavr")
+        .args(args)
+        .status()
+        .expect("Couldn't run `git`");
+
+    if !status.success() {
+        panic!(
+            "`git {}` returned a non-zero exit code",
+            args.iter()
+                .map(|arg| arg.to_string())
+                .collect::<Vec<_>>()
+                .join(" ")
+        );
+    }
+}
diff --git a/patches/twi-inconsistencies.patch b/patches/twi-inconsistencies.patch
new file mode 100644
index 0000000..ee7e9f1
--- /dev/null
+++ b/patches/twi-inconsistencies.patch
@@ -0,0 +1,63 @@
+diff --git a/simavr/sim/avr_twi.c b/simavr/sim/avr_twi.c
+index 521c03c..f96dedd 100644
+--- a/simavr/sim/avr_twi.c
++++ b/simavr/sim/avr_twi.c
+@@ -289,11 +289,11 @@ avr_twi_write(
+ 						avr_twi_irq_msg(msgv, p->peer_addr, avr->data[p->r_twdr]));
+ 
+ 				if (do_read) { // read ?
+-					_avr_twi_delay_state(p, 9,
++					_avr_twi_delay_state(p, 0,
+ 							msgv & TWI_COND_ACK ?
+ 									TWI_MRX_DATA_ACK : TWI_MRX_DATA_NACK);
+ 				} else {
+-					_avr_twi_delay_state(p, 9,
++					_avr_twi_delay_state(p, 0,
+ 							p->state & TWI_COND_ACK ?
+ 									TWI_MTX_DATA_ACK : TWI_MTX_DATA_NACK);
+ 				}
+@@ -319,7 +319,7 @@ avr_twi_write(
+ 
+ 			if (p->peer_addr & 1) { // read ?
+ 				p->state |= TWI_COND_READ;	// always allow read to start with
+-				_avr_twi_delay_state(p, 9,
++				_avr_twi_delay_state(p, 0,
+ 						p->state & TWI_COND_ACK ?
+ 								TWI_MRX_ADR_ACK : TWI_MRX_ADR_NACK);
+ 			} else {
+@@ -328,7 +328,7 @@ avr_twi_write(
+ 							p->state & TWI_COND_ACK ?
+ 									TWI_MTX_ADR_ACK : TWI_MTX_ADR_NACK);
+ 				}else{
+-					_avr_twi_delay_state(p, 9,
++					_avr_twi_delay_state(p, 0,
+ 							p->state & TWI_COND_ACK ?
+ 									TWI_MTX_DATA_ACK : TWI_MTX_DATA_NACK);
+ 				}
+@@ -426,7 +426,7 @@ avr_twi_irq_input(
+ 				// INVERSE logic here
+ 				if (!(msg.u.twi.msg & TWI_COND_WRITE))
+ 					p->peer_addr |= 1;
+-				_avr_twi_delay_state(p, 9,
++				_avr_twi_delay_state(p, 0,
+ 					msg.u.twi.msg & TWI_COND_WRITE ?
+ 						TWI_SRX_ADR_ACK : TWI_STX_ADR_ACK );
+ 			}
+@@ -439,7 +439,7 @@ avr_twi_irq_input(
+ 		}
+ 	}
+ 	if (msg.u.twi.msg & TWI_COND_STOP) {
+-		_avr_twi_delay_state(p, 9,
++		_avr_twi_delay_state(p, 0,
+ 			msg.u.twi.msg & TWI_COND_WRITE ?
+ 				TWI_SRX_ADR_ACK : TWI_STX_ADR_ACK );
+ 	}
+@@ -456,7 +456,7 @@ avr_twi_irq_input(
+ 	if (p->state & TWI_COND_SLAVE) {
+ 		if (msg.u.twi.msg & TWI_COND_WRITE) {
+ 			avr->data[p->r_twdr] = msg.u.twi.data;
+-			_avr_twi_delay_state(p, 9, TWI_SRX_ADR_DATA_ACK );
++			_avr_twi_delay_state(p, 0, TWI_SRX_ADR_DATA_ACK );
+ 		}
+ 	} else {
+ 		// receive a data byte from a slave