diff --git a/src/api.rs b/src/api.rs
index 62ae6cb..489e678 100644
--- a/src/api.rs
+++ b/src/api.rs
@@ -199,6 +199,7 @@ pub(crate) unsafe fn yaml_queue_extend(
 /// for destroying the object using the yaml_parser_delete() function.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_parser_initialize(parser: *mut yaml_parser_t) -> libc::c_int {
     __assert!(!parser.is_null());
     memset(
@@ -567,6 +568,7 @@ pub unsafe fn yaml_parser_set_encoding(mut parser: *mut yaml_parser_t, encoding:
 /// for destroying the object using the yaml_emitter_delete() function.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_emitter_initialize(mut emitter: *mut yaml_emitter_t) -> libc::c_int {
     __assert!(!emitter.is_null());
     memset(
@@ -1000,6 +1002,7 @@ unsafe fn yaml_check_utf8(start: *const yaml_char_t, length: size_t) -> libc::c_
 /// Create the STREAM-START event.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_stream_start_event_initialize(
     mut event: *mut yaml_event_t,
     encoding: yaml_encoding_t,
@@ -1025,6 +1028,7 @@ pub unsafe fn yaml_stream_start_event_initialize(
 /// Create the STREAM-END event.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_stream_end_event_initialize(mut event: *mut yaml_event_t) -> libc::c_int {
     let mark = yaml_mark_t {
         index: 0_u64,
@@ -1049,6 +1053,7 @@ pub unsafe fn yaml_stream_end_event_initialize(mut event: *mut yaml_event_t) ->
 /// ignored by the emitter.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_document_start_event_initialize(
     mut event: *mut yaml_event_t,
     version_directive: *mut yaml_version_directive_t,
@@ -1220,6 +1225,7 @@ pub unsafe fn yaml_document_start_event_initialize(
 /// ignored by the emitter.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_document_end_event_initialize(
     mut event: *mut yaml_event_t,
     implicit: libc::c_int,
@@ -1245,6 +1251,7 @@ pub unsafe fn yaml_document_end_event_initialize(
 /// Create an ALIAS event.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_alias_event_initialize(
     mut event: *mut yaml_event_t,
     anchor: *const yaml_char_t,
@@ -1284,6 +1291,7 @@ pub unsafe fn yaml_alias_event_initialize(
 /// `quoted_implicit` flags must be set.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_scalar_event_initialize(
     mut event: *mut yaml_event_t,
     anchor: *const yaml_char_t,
@@ -1390,6 +1398,7 @@ pub unsafe fn yaml_scalar_event_initialize(
 /// Either the `tag` attribute or the `implicit` flag must be set.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_sequence_start_event_initialize(
     mut event: *mut yaml_event_t,
     anchor: *const yaml_char_t,
@@ -1467,6 +1476,7 @@ pub unsafe fn yaml_sequence_start_event_initialize(
 /// Create a SEQUENCE-END event.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_sequence_end_event_initialize(mut event: *mut yaml_event_t) -> libc::c_int {
     let mark = yaml_mark_t {
         index: 0_u64,
@@ -1492,6 +1502,7 @@ pub unsafe fn yaml_sequence_end_event_initialize(mut event: *mut yaml_event_t) -
 /// Either the `tag` attribute or the `implicit` flag must be set.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_mapping_start_event_initialize(
     mut event: *mut yaml_event_t,
     anchor: *const yaml_char_t,
@@ -1569,6 +1580,7 @@ pub unsafe fn yaml_mapping_start_event_initialize(
 /// Create a MAPPING-END event.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_mapping_end_event_initialize(mut event: *mut yaml_event_t) -> libc::c_int {
     let mark = yaml_mark_t {
         index: 0_u64,
@@ -1630,6 +1642,7 @@ pub unsafe fn yaml_event_delete(event: *mut yaml_event_t) {
 /// Create a YAML document.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_document_initialize(
     mut document: *mut yaml_document_t,
     version_directive: *mut yaml_version_directive_t,
@@ -1930,6 +1943,7 @@ pub unsafe fn yaml_document_get_root_node(document: *mut yaml_document_t) -> *mu
 /// The `style` argument may be ignored by the emitter.
 ///
 /// Returns the node id or 0 on error.
+#[must_use]
 pub unsafe fn yaml_document_add_scalar(
     document: *mut yaml_document_t,
     mut tag: *const yaml_char_t,
@@ -2015,6 +2029,7 @@ pub unsafe fn yaml_document_add_scalar(
 /// The `style` argument may be ignored by the emitter.
 ///
 /// Returns the node id or 0 on error.
+#[must_use]
 pub unsafe fn yaml_document_add_sequence(
     document: *mut yaml_document_t,
     mut tag: *const yaml_char_t,
@@ -2109,6 +2124,7 @@ pub unsafe fn yaml_document_add_sequence(
 /// The `style` argument may be ignored by the emitter.
 ///
 /// Returns the node id or 0 on error.
+#[must_use]
 pub unsafe fn yaml_document_add_mapping(
     document: *mut yaml_document_t,
     mut tag: *const yaml_char_t,
@@ -2201,6 +2217,7 @@ pub unsafe fn yaml_document_add_mapping(
 /// Add an item to a SEQUENCE node.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_document_append_sequence_item(
     document: *mut yaml_document_t,
     sequence: libc::c_int,
@@ -2282,6 +2299,7 @@ pub unsafe fn yaml_document_append_sequence_item(
 /// Add a pair of a key and a value to a MAPPING node.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_document_append_mapping_pair(
     document: *mut yaml_document_t,
     mapping: libc::c_int,
diff --git a/src/dumper.rs b/src/dumper.rs
index 9eabe8b..41147e1 100644
--- a/src/dumper.rs
+++ b/src/dumper.rs
@@ -17,6 +17,7 @@ use core::ptr::{self, addr_of_mut};
 /// This function should be used before yaml_emitter_dump() is called.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_emitter_open(mut emitter: *mut yaml_emitter_t) -> libc::c_int {
     let mut event = MaybeUninit::<yaml_event_t>::uninit();
     let event = event.as_mut_ptr();
@@ -48,6 +49,7 @@ pub unsafe fn yaml_emitter_open(mut emitter: *mut yaml_emitter_t) -> libc::c_int
 /// This function should be used after yaml_emitter_dump() is called.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_emitter_close(mut emitter: *mut yaml_emitter_t) -> libc::c_int {
     let mut event = MaybeUninit::<yaml_event_t>::uninit();
     let event = event.as_mut_ptr();
@@ -84,6 +86,7 @@ pub unsafe fn yaml_emitter_close(mut emitter: *mut yaml_emitter_t) -> libc::c_in
 /// emitted. The document object is destroyed even if the function fails.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_emitter_dump(
     emitter: *mut yaml_emitter_t,
     document: *mut yaml_document_t,
diff --git a/src/emitter.rs b/src/emitter.rs
index fda5635..7d6d827 100644
--- a/src/emitter.rs
+++ b/src/emitter.rs
@@ -39,6 +39,7 @@ unsafe fn yaml_emitter_set_emitter_error(
 /// function fails.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_emitter_emit(
     mut emitter: *mut yaml_emitter_t,
     event: *mut yaml_event_t,
diff --git a/src/loader.rs b/src/loader.rs
index 5932ddb..ef2bf4b 100644
--- a/src/loader.rs
+++ b/src/loader.rs
@@ -34,6 +34,7 @@ struct loader_ctx {
 /// the parser.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_parser_load(
     mut parser: *mut yaml_parser_t,
     document: *mut yaml_document_t,
diff --git a/src/parser.rs b/src/parser.rs
index ea9ace3..5eb0c9b 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -45,6 +45,7 @@ use core::ptr::{self, addr_of_mut};
 /// parser.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_parser_parse(
     parser: *mut yaml_parser_t,
     event: *mut yaml_event_t,
diff --git a/src/scanner.rs b/src/scanner.rs
index a7cfe83..fd5ea83 100644
--- a/src/scanner.rs
+++ b/src/scanner.rs
@@ -34,6 +34,7 @@ use core::ptr::{self, addr_of_mut};
 /// the parser.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_parser_scan(
     mut parser: *mut yaml_parser_t,
     token: *mut yaml_token_t,
diff --git a/src/writer.rs b/src/writer.rs
index 2a8d883..8de8bf9 100644
--- a/src/writer.rs
+++ b/src/writer.rs
@@ -17,6 +17,7 @@ unsafe fn yaml_emitter_set_writer_error(
 /// Flush the accumulated characters to the output.
 ///
 /// Returns 1 if the function succeeded, 0 on error.
+#[must_use]
 pub unsafe fn yaml_emitter_flush(emitter: *mut yaml_emitter_t) -> libc::c_int {
     __assert!(!emitter.is_null());
     __assert!(((*emitter).write_handler).is_some());