diff --git a/NEWS b/NEWS
index 056756a8348..06aa7adcc02 100644
--- a/NEWS
+++ b/NEWS
@@ -30,6 +30,12 @@ PHP                                                                        NEWS
   . Fix some deprecations on newer libxml versions regarding input
     buffer/parser handling. (ndossche)
 
+- MbString:
+  . Fixed bug GH-20491 (SLES15 compile error with mbstring oniguruma).
+    (ndossche)
+  . Fixed bug GH-20492 (mbstring compile warning due to non-strings).
+    (ndossche)
+
 - Opcache:
   . Fixed bug GH-20329 (opcache.file_cache broken with full interned string
     buffer). (Arnaud)
diff --git a/ext/mbstring/libmbfl/filters/mbfilter_cjk.c b/ext/mbstring/libmbfl/filters/mbfilter_cjk.c
index bc14fe48f2c..1c158a852c3 100644
--- a/ext/mbstring/libmbfl/filters/mbfilter_cjk.c
+++ b/ext/mbstring/libmbfl/filters/mbfilter_cjk.c
@@ -21,15 +21,21 @@
  * This macro converts uppercase ASCII values to Regional Indicator codepoints */
 #define NFLAGS(c) (0x1F1A5+((unsigned int)(c)))
 
-static const char nflags_s[10][2] = {"CN", "DE", "ES", "FR", "GB", "IT", "JP", "KR", "RU", "US"};
+#if __has_attribute(nonstring) && defined(__GNUC__) && ((!defined(__clang__) && __GNUC__ >= 15) || (defined(__clang_major__) && __clang_major__ >= 20))
+# define ZEND_NONSTRING __attribute__((nonstring))
+#else
+# define ZEND_NONSTRING
+#endif
+
+static const char nflags_s[10][2] ZEND_NONSTRING = {"CN", "DE", "ES", "FR", "GB", "IT", "JP", "KR", "RU", "US"};
 static const int nflags_code_kddi[10] = { 0x2549, 0x2546, 0x24C0, 0x2545, 0x2548, 0x2547, 0x2750, 0x254A, 0x24C1, 0x27F7 };
 static const int nflags_code_sb[10] = { 0x2B0A, 0x2B05, 0x2B08, 0x2B04, 0x2B07, 0x2B06, 0x2B02, 0x2B0B, 0x2B09, 0x2B03 };
 
 #define EMIT_KEYPAD_EMOJI(c) do { *snd = (c); return 0x20E3; } while(0)
 #define EMIT_FLAG_EMOJI(country) do { *snd = NFLAGS((country)[0]); return NFLAGS((country)[1]); } while(0)
 
-static const char nflags_kddi[6][2] = {"FR", "DE", "IT", "GB", "CN", "KR"};
-static const char nflags_sb[10][2] = {"JP", "US", "FR", "DE", "IT", "GB", "ES", "RU", "CN", "KR"};
+static const char nflags_kddi[6][2] ZEND_NONSTRING = {"FR", "DE", "IT", "GB", "CN", "KR"};
+static const char nflags_sb[10][2] ZEND_NONSTRING = {"JP", "US", "FR", "DE", "IT", "GB", "ES", "RU", "CN", "KR"};
 
 /* number -> (ku*94)+ten value for telephone keypad character */
 #define DOCOMO_KEYPAD(n) ((n) == 0 ? 0x296F : (0x2965 + (n)))
diff --git a/ext/mbstring/libmbfl/filters/mbfilter_utf8.c b/ext/mbstring/libmbfl/filters/mbfilter_utf8.c
index 0786c8e7f31..b0a9b6f95a3 100644
--- a/ext/mbstring/libmbfl/filters/mbfilter_utf8.c
+++ b/ext/mbstring/libmbfl/filters/mbfilter_utf8.c
@@ -725,7 +725,13 @@ static int mbfl_filt_conv_wchar_utf8_mobile(int c, mbfl_convert_filter *filter)
  * This macro converts uppercase ASCII values to Regional Indicator codepoints */
 #define NFLAGS(c) (0x1F1A5+(int)(c))
 
-static const char nflags_s[10][2] = {"CN","DE","ES","FR","GB","IT","JP","KR","RU","US"};
+#if __has_attribute(nonstring) && defined(__GNUC__) && ((!defined(__clang__) && __GNUC__ >= 15) || (defined(__clang_major__) && __clang_major__ >= 20))
+# define ZEND_NONSTRING __attribute__((nonstring))
+#else
+# define ZEND_NONSTRING
+#endif
+
+static const char nflags_s[10][2] ZEND_NONSTRING = {"CN","DE","ES","FR","GB","IT","JP","KR","RU","US"};
 static const int nflags_code_kddi[10] = { 0x2549, 0x2546, 0x24C0, 0x2545, 0x2548, 0x2547, 0x2750, 0x254A, 0x24C1, 0x27F7 };
 static const int nflags_code_sb[10] = { 0x2B0A, 0x2B05, 0x2B08, 0x2B04, 0x2B07, 0x2B06, 0x2B02, 0x2B0B, 0x2B09, 0x2B03 };
 
diff --git a/ext/mbstring/php_onig_compat.h b/ext/mbstring/php_onig_compat.h
index c97ba0c5cb6..5a1fa8eeaaf 100644
--- a/ext/mbstring/php_onig_compat.h
+++ b/ext/mbstring/php_onig_compat.h
@@ -5,4 +5,10 @@
 #define regex_t                     php_mb_regex_t
 #define re_registers                php_mb_re_registers
 
+/* Required for some distros that conditionally override PV_.
+ * As we're in C99 this header is always available. */
+#ifndef HAVE_STDARG_H
+# define HAVE_STDARG_H
+#endif
+
 #endif /* _PHP_ONIG_COMPAT_H */