diff --git a/Cargo.toml b/Cargo.toml
index d27a410..ed937e8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -25,6 +25,7 @@ all = [
     "strncmp",
     "strncasecmp",
     "strcpy",
+    "strcat",
     "strncpy",
     "strlen",
     "strtol",
@@ -35,6 +36,7 @@ all = [
     "strtoumax",
     "strstr",
     "strchr",
+    "strrchr",
     "atoi",
     "utoa",
     "itoa",
@@ -51,6 +53,7 @@ strcmp = []
 strncmp = []
 strncasecmp = []
 strcpy = []
+strcat = []
 strncpy = []
 strlen = []
 strtol = []
@@ -61,6 +64,7 @@ strtoimax = []
 strtoumax = []
 strstr = []
 strchr = []
+strrchr = []
 atoi = []
 utoa = []
 itoa = []
diff --git a/README.md b/README.md
index 5f02ccd..ca09ba4 100644
--- a/README.md
+++ b/README.md
@@ -19,6 +19,7 @@ This crate basically came about so that the [nrfxlib](https://github.com/NordicP
 * strcmp
 * strncmp
 * strncasecmp
+* strcat
 * strcpy
 * strncpy
 * strlen
@@ -30,6 +31,7 @@ This crate basically came about so that the [nrfxlib](https://github.com/NordicP
 * strtoumax
 * strstr
 * strchr
+* strrchr
 * snprintf
 * vsnprintf
 * qsort
diff --git a/src/lib.rs b/src/lib.rs
index 4532aa6..8198eef 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -50,6 +50,10 @@ mod strlen;
 #[cfg(feature = "strlen")]
 pub use self::strlen::strlen;
 
+mod strcat;
+#[cfg(feature = "strcat")]
+pub use self::strcat::strcat;
+
 mod strtol;
 #[cfg(feature = "atoi")]
 pub use self::strtol::atoi;
@@ -82,6 +86,10 @@ mod strchr;
 #[cfg(feature = "strchr")]
 pub use self::strchr::strchr;
 
+mod strrchr;
+#[cfg(feature = "strrchr")]
+pub use self::strrchr::strrchr;
+
 mod qsort;
 #[cfg(feature = "qsort")]
 pub use self::qsort::qsort;
diff --git a/src/strcat.rs b/src/strcat.rs
new file mode 100644
index 0000000..7731067
--- /dev/null
+++ b/src/strcat.rs
@@ -0,0 +1,29 @@
+//! Rust implementation of C library function `strcat`
+//!
+//! Licensed under the Blue Oak Model Licence 1.0.0
+
+use crate::CChar;
+
+/// Rust implementation of C library function `strcat`. Passing NULL
+/// (core::ptr::null()) gives undefined behaviour.
+#[cfg_attr(feature = "strcat", no_mangle)]
+pub unsafe extern "C" fn strcat(dest: *mut CChar, src: *const CChar) -> *const CChar {
+	crate::strcpy::strcpy(dest.add(crate::strlen::strlen(dest)), src);
+	dest
+}
+
+#[cfg(test)]
+mod test {
+	use super::*;
+
+	#[test]
+	fn simple() {
+		let mut dest = *b"hello\0\0\0\0\0\0\0\0";
+		let src = *b" world\0";
+		let result = unsafe { strcat(dest.as_mut_ptr(), src.as_ptr()) };
+		assert_eq!(
+			unsafe { core::slice::from_raw_parts(result, 12) },
+			b"hello world\0"
+		);
+	}
+}
diff --git a/src/strchr.rs b/src/strchr.rs
index 063c96a..23efe0a 100644
--- a/src/strchr.rs
+++ b/src/strchr.rs
@@ -25,37 +25,37 @@ mod test {
 	use super::*;
 
 	#[test]
-	fn no_match() {
-		let haystack = b"haystack\0".as_ptr();
+	fn strchr_no_match() {
+		let haystack = b"hayyystack\0".as_ptr();
 		let result = unsafe { strchr(haystack, b'X' as CInt) };
 		assert_eq!(result, core::ptr::null());
 	}
 
 	#[test]
-	fn null() {
-		let haystack = b"haystack\0".as_ptr();
+	fn strchr_null() {
+		let haystack = b"hayyystack\0".as_ptr();
 		let result = unsafe { strchr(haystack, 0) };
-		assert_eq!(result, unsafe { haystack.offset(8) });
+		assert_eq!(result, unsafe { haystack.offset(10) });
 	}
 
 	#[test]
-	fn start() {
-		let haystack = b"haystack\0".as_ptr();
+	fn strchr_start() {
+		let haystack = b"hayyystack\0".as_ptr();
 		let result = unsafe { strchr(haystack, b'h' as CInt) };
 		assert_eq!(result, haystack);
 	}
 
 	#[test]
-	fn middle() {
-		let haystack = b"haystack\0".as_ptr();
+	fn strchr_middle() {
+		let haystack = b"hayyystack\0".as_ptr();
 		let result = unsafe { strchr(haystack, b'y' as CInt) };
 		assert_eq!(result, unsafe { haystack.offset(2) });
 	}
 
 	#[test]
-	fn end() {
-		let haystack = b"haystack\0".as_ptr();
+	fn strchr_end() {
+		let haystack = b"hayyystack\0".as_ptr();
 		let result = unsafe { strchr(haystack, b'k' as CInt) };
-		assert_eq!(result, unsafe { haystack.offset(7) });
+		assert_eq!(result, unsafe { haystack.offset(9) });
 	}
 }
diff --git a/src/strrchr.rs b/src/strrchr.rs
new file mode 100644
index 0000000..2cf42fb
--- /dev/null
+++ b/src/strrchr.rs
@@ -0,0 +1,62 @@
+//! Rust implementation of C library function `strchr`
+//!
+//! Copyright (c) 42 Technology Ltd
+//! Licensed under the Blue Oak Model Licence 1.0.0
+
+use crate::{CChar, CInt};
+
+/// Rust implementation of C library function `strrchr`
+#[cfg_attr(feature = "strrchr", no_mangle)]
+pub unsafe extern "C" fn strrchr(haystack: *const CChar, needle: CInt) -> *const CChar {
+	let mut last = core::ptr::null();
+	for idx in 0.. {
+		let ptr = haystack.offset(idx);
+		if needle == (*ptr) as CInt {
+			last = ptr;
+		}
+		if (*ptr) == 0 {
+			break;
+		}
+	}
+	last
+}
+
+#[cfg(test)]
+mod test {
+	use super::*;
+
+	#[test]
+	fn strrchr_no_match() {
+		let haystack = b"hayyystack\0".as_ptr();
+		let result = unsafe { strrchr(haystack, b'X' as CInt) };
+		assert_eq!(result, core::ptr::null());
+	}
+
+	#[test]
+	fn strrchr_null() {
+		let haystack = b"hayyystack\0".as_ptr();
+		let result = unsafe { strrchr(haystack, 0) };
+		assert_eq!(result, unsafe { haystack.offset(10) });
+	}
+
+	#[test]
+	fn strrchr_start() {
+		let haystack = b"hayhay\0".as_ptr();
+		let result = unsafe { strrchr(haystack, b'h' as CInt) };
+		assert_eq!(result, unsafe { haystack.offset(3) });
+	}
+
+	#[test]
+	fn strrchr_middle() {
+		let haystack = b"hayyystack\0".as_ptr();
+		let result = unsafe { strrchr(haystack, b'y' as CInt) };
+		assert_eq!(result, unsafe { haystack.offset(4) });
+	}
+
+	#[test]
+	fn strrchr_end() {
+		let haystack = b"hayyystack\0".as_ptr();
+		let result = unsafe { strrchr(haystack, b'k' as CInt) };
+		assert_eq!(result, unsafe { haystack.offset(9) });
+	}
+}