diff --git a/src/templ.rs b/src/templ.rs
index 6048dd898..1263178fe 100644
--- a/src/templ.rs
+++ b/src/templ.rs
@@ -79,7 +79,11 @@ macro_rules! string_array_arg {
 	($name: ident) => {
 		let $name = $name
 			.iter()
-			.map(|x| x.as_ptr().cast::<::std::ffi::c_char>())
+			.map(|x| ::std::ffi::CString::new(*x).expect("invalid C string"))
+			.collect::<::std::vec::Vec<_>>();
+		let $name = $name
+			.iter()
+			.map(|x| x.as_ptr())
 			.collect::<::std::vec::Vec<_>>();
 	};
 }
@@ -87,9 +91,14 @@ macro_rules! string_array_arg {
 #[allow(unused_macros)]
 macro_rules! string_array_arg_mut {
 	($name: ident) => {
+		let $name = $name
+			.iter()
+			.map(|x| ::std::ffi::CString::new(*x).expect("invalid C string"))
+			.collect::<::std::vec::Vec<_>>();
+		// Casting to mut below trusts on undefined CString behavior.
 		let mut $name = $name
 			.iter()
-			.map(|x| x.as_ptr().cast::<::std::ffi::c_char>().cast_mut())
+			.map(|x| x.as_ptr().cast_mut())
 			.collect::<::std::vec::Vec<_>>();
 	};
 }