diff --git a/ext/date/extconf.rb b/ext/date/extconf.rb
index 8a1467df09e402..3ab534f833edfd 100644
--- a/ext/date/extconf.rb
+++ b/ext/date/extconf.rb
@@ -3,6 +3,9 @@
 
 config_string("strict_warnflags") {|w| $warnflags += " #{w}"}
 
+unless try_compile("", "", werror: true)
+  append_cflags("-Wno-default-const-init-field-unsafe")
+end
 append_cflags("-Wno-compound-token-split-by-macro") if RUBY_VERSION < "2.7."
 have_func("rb_category_warn")
 with_werror("", {:werror => true}) do |opt, |
diff --git a/hash.c b/hash.c
index 3ca035595d8231..172ed3bd49a502 100644
--- a/hash.c
+++ b/hash.c
@@ -654,7 +654,7 @@ ar_hint_first_match(ar_hint_t needle, VALUE haystack)
 {
     // Common SWAR technique.
     // First XOR all bytes so that matching ones are set to 0x00.
-    VALUE search_mask = AR_HINT_BASE_MASK * needle;
+    VALUE search_mask = (VALUE)AR_HINT_BASE_MASK * needle;
     VALUE matches = haystack ^ search_mask;
 
     // Then turns 0x00 into 0x80, and any other bytes into 0x00.
diff --git a/parse.y b/parse.y
index c726402e0fbd3c..7a566681964070 100644
--- a/parse.y
+++ b/parse.y
@@ -6817,7 +6817,7 @@ rb_parser_str_escape(struct parser_params *p, rb_parser_string_t *str)
             if (pend < ptr + n)
                 n = (int)(pend - ptr);
             while (n--) {
-                c = *ptr & 0xf0 >> 4;
+                c = ((unsigned char)*ptr >> 4) & 0x0f;
                 charbuf[2] = (c < 10) ? '0' + c : 'A' + c - 10;
                 c = *ptr & 0x0f;
                 charbuf[3] = (c < 10) ? '0' + c : 'A' + c - 10;