diff --git a/src/backend/columnar/columnar_metadata.c b/src/backend/columnar/columnar_metadata.c
index a11138d0d..1afd6af55 100644
--- a/src/backend/columnar/columnar_metadata.c
+++ b/src/backend/columnar/columnar_metadata.c
@@ -645,10 +645,10 @@ SaveStripeSkipList(RelFileLocator relfilelocator, uint64 stripe,
 			{
 				values[Anum_columnar_chunk_minimum_value - 1] =
 					PointerGetDatum(DatumToBytea(chunk->minimumValue,
-												 &tupleDescriptor->attrs[columnIndex]));
+												 Attr(tupleDescriptor, columnIndex)));
 				values[Anum_columnar_chunk_maximum_value - 1] =
 					PointerGetDatum(DatumToBytea(chunk->maximumValue,
-												 &tupleDescriptor->attrs[columnIndex]));
+												 Attr(tupleDescriptor, columnIndex)));
 			}
 			else
 			{
@@ -803,9 +803,9 @@ ReadStripeSkipList(RelFileLocator relfilelocator, uint64 stripe,
 				datumArray[Anum_columnar_chunk_maximum_value - 1]);
 
 			chunk->minimumValue =
-				ByteaToDatum(minValue, &tupleDescriptor->attrs[columnIndex]);
+				ByteaToDatum(minValue, Attr(tupleDescriptor, columnIndex));
 			chunk->maximumValue =
-				ByteaToDatum(maxValue, &tupleDescriptor->attrs[columnIndex]);
+				ByteaToDatum(maxValue, Attr(tupleDescriptor, columnIndex));
 
 			chunk->hasMinMax = true;
 		}
diff --git a/src/include/columnar/columnar_version_compat.h b/src/include/columnar/columnar_version_compat.h
index d6908aced..640170297 100644
--- a/src/include/columnar/columnar_version_compat.h
+++ b/src/include/columnar/columnar_version_compat.h
@@ -9,14 +9,27 @@
  *-------------------------------------------------------------------------
  */
 
-#ifndef COLUMNAR_COMPAT_H
-#define COLUMNAR_COMPAT_H
+ #ifndef COLUMNAR_VERSION_COMPAT_H
+ #define COLUMNAR_VERSION_COMPAT_H
 
 #include "pg_version_constants.h"
 
+/* for PG_VERSION_NUM and TupleDescAttr() */
+#include "postgres.h"
+#include "access/htup_details.h"
+
+
 #define ACLCHECK_OBJECT_TABLE OBJECT_TABLE
 
 #define ExplainPropertyLong(qlabel, value, es) \
 	ExplainPropertyInteger(qlabel, NULL, value, es)
 
+
+/* tuple-descriptor attributes moved in PostgreSQL 18: */
+#if PG_VERSION_NUM >= 180000
+# define Attr(tupdesc, colno)  TupleDescAttr((tupdesc), (colno))
+#else
+# define Attr(tupdesc, colno)  ((tupdesc)->attrs[(colno)])
+#endif
+
 #endif /* COLUMNAR_COMPAT_H */