diff --git a/NEWS b/NEWS
index b593a1827b1..c4a6378163c 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,8 @@ PHP                                                                        NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? ????, PHP 8.4.19
 
+- Core:
+  . Fixed bug GH-21029 (zend_mm_heap corrupted on Aarch64, LTO builds). (Arnaud)
 
 12 Feb 2026, PHP 8.4.18
 
diff --git a/Zend/zend_multiply.h b/Zend/zend_multiply.h
index 3e730042e7a..d536d3247f6 100644
--- a/Zend/zend_multiply.h
+++ b/Zend/zend_multiply.h
@@ -267,7 +267,8 @@ static zend_always_inline size_t zend_safe_address(size_t nmemb, size_t size, si
 		: "=&r"(res), "=&r"(m_overflow)
 		: "r"(nmemb),
 		  "r"(size),
-		  "r"(offset));
+		  "r"(offset)
+		: "cc");
 
 	if (UNEXPECTED(m_overflow)) {
 		*overflow = 1;
@@ -291,7 +292,8 @@ static zend_always_inline size_t zend_safe_address(size_t nmemb, size_t size, si
              : "=&r"(res), "=&r"(m_overflow)
              : "r"(nmemb),
                "r"(size),
-               "r"(offset));
+               "r"(offset)
+             : "xer");
 
         if (UNEXPECTED(m_overflow)) {
                 *overflow = 1;