diff --git a/CHANGES b/CHANGES
index 6b3d562330..56c51bce25 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,7 @@
+4565.	[cleanup]	The inline macro versions of isc_buffer_put*()
+			did not implement automatic buffer reallocation.
+			[RT #44216]
+
 4564.	[maint]		Update the built in managed keys to include the
 			upcoming root KSK. [RT #44579]
 			
diff --git a/lib/isc/buffer.c b/lib/isc/buffer.c
index 1e2eac0cff..7337ab43e8 100644
--- a/lib/isc/buffer.c
+++ b/lib/isc/buffer.c
@@ -281,7 +281,7 @@ void
 isc__buffer_putuint8(isc_buffer_t *b, isc_uint8_t val) {
 	isc_result_t result;
 	REQUIRE(ISC_BUFFER_VALID(b));
-	if (b->autore) {
+	if (ISC_UNLIKELY(b->autore)) {
 		result = isc_buffer_reserve(&b, 1);
 		REQUIRE(result == ISC_R_SUCCESS);
 	}
@@ -315,7 +315,7 @@ void
 isc__buffer_putuint16(isc_buffer_t *b, isc_uint16_t val) {
 	isc_result_t result;
 	REQUIRE(ISC_BUFFER_VALID(b));
-	if (b->autore) {
+	if (ISC_UNLIKELY(b->autore)) {
 		result = isc_buffer_reserve(&b, 2);
 		REQUIRE(result == ISC_R_SUCCESS);
 	}
@@ -328,7 +328,7 @@ void
 isc__buffer_putuint24(isc_buffer_t *b, isc_uint32_t val) {
 	isc_result_t result;
 	REQUIRE(ISC_BUFFER_VALID(b));
-	if (b->autore) {
+	if (ISC_UNLIKELY(b->autore)) {
 		result = isc_buffer_reserve(&b, 3);
 		REQUIRE(result == ISC_R_SUCCESS);
 	}
@@ -364,7 +364,7 @@ void
 isc__buffer_putuint32(isc_buffer_t *b, isc_uint32_t val) {
 	isc_result_t result;
 	REQUIRE(ISC_BUFFER_VALID(b));
-	if (b->autore) {
+	if (ISC_UNLIKELY(b->autore)) {
 		result = isc_buffer_reserve(&b, 4);
 		REQUIRE(result == ISC_R_SUCCESS);
 	}
@@ -405,7 +405,7 @@ isc__buffer_putuint48(isc_buffer_t *b, isc_uint64_t val) {
 	isc_uint32_t vallo;
 
 	REQUIRE(ISC_BUFFER_VALID(b));
-	if (b->autore) {
+	if (ISC_UNLIKELY(b->autore)) {
 		result = isc_buffer_reserve(&b, 6);
 		REQUIRE(result == ISC_R_SUCCESS);
 	}
@@ -423,7 +423,7 @@ isc__buffer_putmem(isc_buffer_t *b, const unsigned char *base,
 {
 	isc_result_t result;
 	REQUIRE(ISC_BUFFER_VALID(b));
-	if (b->autore) {
+	if (ISC_UNLIKELY(b->autore)) {
 		result = isc_buffer_reserve(&b, length);
 		REQUIRE(result == ISC_R_SUCCESS);
 	}
@@ -445,7 +445,7 @@ isc__buffer_putstr(isc_buffer_t *b, const char *source) {
 	 * Do not use ISC__BUFFER_PUTSTR(), so strlen is only done once.
 	 */
 	l = strlen(source);
-	if (b->autore) {
+	if (ISC_UNLIKELY(b->autore)) {
 		result = isc_buffer_reserve(&b, l);
 		REQUIRE(result == ISC_R_SUCCESS);
 	}
@@ -468,7 +468,7 @@ isc_buffer_putdecint(isc_buffer_t *b, isc_int64_t v) {
 	/* xxxwpk do it more low-level way ? */
 	l = snprintf(buf, 21, "%" ISC_PRINT_QUADFORMAT "d", v);
 	RUNTIME_CHECK(l <= 21);
-	if (b->autore) {
+	if (ISC_UNLIKELY(b->autore)) {
 		result = isc_buffer_reserve(&b, l);
 		REQUIRE(result == ISC_R_SUCCESS);
 	}
@@ -514,7 +514,7 @@ isc_buffer_copyregion(isc_buffer_t *b, const isc_region_t *r) {
 	 */
 	base = isc_buffer_used(b);
 	available = isc_buffer_availablelength(b);
-	if (b->autore) {
+	if (ISC_UNLIKELY(b->autore)) {
 		result = isc_buffer_reserve(&b, r->length);
 		if (result != ISC_R_SUCCESS)
 			return (result);
diff --git a/lib/isc/include/isc/buffer.h b/lib/isc/include/isc/buffer.h
index eb6684de06..73e35a0e23 100644
--- a/lib/isc/include/isc/buffer.h
+++ b/lib/isc/include/isc/buffer.h
@@ -876,6 +876,11 @@ ISC_LANG_ENDDECLS
 
 #define ISC__BUFFER_PUTMEM(_b, _base, _length) \
 	do { \
+		if (ISC_UNLIKELY((_b)->autore)) { \
+			REQUIRE(isc_buffer_reserve(&(_b), _length) \
+				== ISC_R_SUCCESS); \
+		} \
+		REQUIRE(isc_buffer_availablelength(_b) >= _length); \
 		memmove(isc_buffer_used(_b), (_base), (_length)); \
 		(_b)->used += (_length); \
 	} while (0)
@@ -885,6 +890,11 @@ ISC_LANG_ENDDECLS
 		unsigned int _length; \
 		unsigned char *_cp; \
 		_length = strlen(_source); \
+		if (ISC_UNLIKELY((_b)->autore)) { \
+			REQUIRE(isc_buffer_reserve(&(_b), _length) \
+				== ISC_R_SUCCESS); \
+		} \
+		REQUIRE(isc_buffer_availablelength(_b) >= _length); \
 		_cp = isc_buffer_used(_b); \
 		memmove(_cp, (_source), _length); \
 		(_b)->used += (_length); \
@@ -894,6 +904,11 @@ ISC_LANG_ENDDECLS
 	do { \
 		unsigned char *_cp; \
 		isc_uint8_t _val2 = (_val); \
+		if (ISC_UNLIKELY((_b)->autore)) { \
+			REQUIRE(isc_buffer_reserve(&(_b), 1) \
+				== ISC_R_SUCCESS); \
+		} \
+		REQUIRE(isc_buffer_availablelength(_b) >= 1); \
 		_cp = isc_buffer_used(_b); \
 		(_b)->used++; \
 		_cp[0] = _val2 & 0x00ff; \
@@ -903,6 +918,10 @@ ISC_LANG_ENDDECLS
 	do { \
 		unsigned char *_cp; \
 		isc_uint16_t _val2 = (_val); \
+		if (ISC_UNLIKELY((_b)->autore)) { \
+			REQUIRE(isc_buffer_reserve(&(_b), 2) == ISC_R_SUCCESS); \
+		} \
+		REQUIRE(isc_buffer_availablelength(_b) >= 2); \
 		_cp = isc_buffer_used(_b); \
 		(_b)->used += 2; \
 		_cp[0] = (unsigned char)((_val2 & 0xff00U) >> 8); \
@@ -913,6 +932,11 @@ ISC_LANG_ENDDECLS
 	do { \
 		unsigned char *_cp; \
 		isc_uint32_t _val2 = (_val); \
+		if (ISC_UNLIKELY((_b)->autore)) { \
+			REQUIRE(isc_buffer_reserve(&(_b), 3) \
+				== ISC_R_SUCCESS); \
+		} \
+		REQUIRE(isc_buffer_availablelength(_b) >= 3); \
 		_cp = isc_buffer_used(_b); \
 		(_b)->used += 3; \
 		_cp[0] = (unsigned char)((_val2 & 0xff0000U) >> 16); \
@@ -924,6 +948,11 @@ ISC_LANG_ENDDECLS
 	do { \
 		unsigned char *_cp; \
 		isc_uint32_t _val2 = (_val); \
+		if (ISC_UNLIKELY((_b)->autore)) { \
+			REQUIRE(isc_buffer_reserve(&(_b), 4) \
+				== ISC_R_SUCCESS); \
+		} \
+		REQUIRE(isc_buffer_availablelength(_b) >= 4); \
 		_cp = isc_buffer_used(_b); \
 		(_b)->used += 4; \
 		_cp[0] = (unsigned char)((_val2 & 0xff000000) >> 24); \