diff --git a/ext/psych/yaml/emitter.c b/ext/psych/yaml/emitter.c
index c852f9309f..bf84fafc51 100644
--- a/ext/psych/yaml/emitter.c
+++ b/ext/psych/yaml/emitter.c
@@ -53,7 +53,7 @@
 #define WRITE_BREAK(emitter,string)                                             \
     (FLUSH(emitter)                                                             \
      && (CHECK(string,'\n') ?                                                   \
-         (PUT_BREAK(emitter),                                                   \
+         ((void)PUT_BREAK(emitter),                                             \
           string.pointer ++,                                                    \
           1) :                                                                  \
          (COPY(emitter->buffer,string),                                         \
diff --git a/ext/psych/yaml/parser.c b/ext/psych/yaml/parser.c
index dc5430b09f..32671b252c 100644
--- a/ext/psych/yaml/parser.c
+++ b/ext/psych/yaml/parser.c
@@ -759,9 +759,8 @@ yaml_parser_parse_block_sequence_entry(yaml_parser_t *parser,
 
     else if (token->type == YAML_BLOCK_END_TOKEN)
     {
-        yaml_mark_t dummy_mark;     /* Used to eliminate a compiler warning. */
         parser->state = POP(parser, parser->states);
-        dummy_mark = POP(parser, parser->marks);
+        (void)POP(parser, parser->marks);
         SEQUENCE_END_EVENT_INIT(*event, token->start_mark, token->end_mark);
         SKIP_TOKEN(parser);
         return 1;
@@ -869,9 +868,8 @@ yaml_parser_parse_block_mapping_key(yaml_parser_t *parser,
 
     else if (token->type == YAML_BLOCK_END_TOKEN)
     {
-        yaml_mark_t dummy_mark;     /* Used to eliminate a compiler warning. */
         parser->state = POP(parser, parser->states);
-        dummy_mark = POP(parser, parser->marks);
+        (void)POP(parser, parser->marks);
         MAPPING_END_EVENT_INIT(*event, token->start_mark, token->end_mark);
         SKIP_TOKEN(parser);
         return 1;
@@ -952,7 +950,6 @@ yaml_parser_parse_flow_sequence_entry(yaml_parser_t *parser,
         yaml_event_t *event, int first)
 {
     yaml_token_t *token;
-    yaml_mark_t dummy_mark;     /* Used to eliminate a compiler warning. */
 
     if (first) {
         token = PEEK_TOKEN(parser);
@@ -997,7 +994,7 @@ yaml_parser_parse_flow_sequence_entry(yaml_parser_t *parser,
     }
 
     parser->state = POP(parser, parser->states);
-    dummy_mark = POP(parser, parser->marks);
+    (void)POP(parser, parser->marks);
     SEQUENCE_END_EVENT_INIT(*event, token->start_mark, token->end_mark);
     SKIP_TOKEN(parser);
     return 1;
@@ -1104,7 +1101,6 @@ yaml_parser_parse_flow_mapping_key(yaml_parser_t *parser,
         yaml_event_t *event, int first)
 {
     yaml_token_t *token;
-    yaml_mark_t dummy_mark;     /* Used to eliminate a compiler warning. */
 
     if (first) {
         token = PEEK_TOKEN(parser);
@@ -1158,7 +1154,7 @@ yaml_parser_parse_flow_mapping_key(yaml_parser_t *parser,
     }
 
     parser->state = POP(parser, parser->states);
-    dummy_mark = POP(parser, parser->marks);
+    (void)POP(parser, parser->marks);
     MAPPING_END_EVENT_INIT(*event, token->start_mark, token->end_mark);
     SKIP_TOKEN(parser);
     return 1;
diff --git a/ext/psych/yaml/scanner.c b/ext/psych/yaml/scanner.c
index 2ca3fed62f..ea29a64b82 100644
--- a/ext/psych/yaml/scanner.c
+++ b/ext/psych/yaml/scanner.c
@@ -1193,11 +1193,9 @@ yaml_parser_increase_flow_level(yaml_parser_t *parser)
 static int
 yaml_parser_decrease_flow_level(yaml_parser_t *parser)
 {
-    yaml_simple_key_t dummy_key;    /* Used to eliminate a compiler warning. */
-
     if (parser->flow_level) {
         parser->flow_level --;
-        dummy_key = POP(parser, parser->simple_keys);
+        (void)POP(parser, parser->simple_keys);
     }
 
     return 1;
diff --git a/ext/psych/yaml/yaml_private.h b/ext/psych/yaml/yaml_private.h
index 21fc5e4326..cd3d3a56c4 100644
--- a/ext/psych/yaml/yaml_private.h
+++ b/ext/psych/yaml/yaml_private.h
@@ -433,7 +433,8 @@ yaml_queue_extend(void **start, void **head, void **tail, void **end);
      (stack).start = (stack).top = (stack).end = 0)
 
 #define STACK_EMPTY(context,stack)                                              \
-    ((stack).start == (stack).top)
+    ((void)(context),                                                           \
+     ((stack).start == (stack).top))
 
 #define STACK_LIMIT(context,stack,size)                                         \
     ((stack).top - (stack).start < (size) ?                                     \