diff --git a/hibernate-core/src/main/java/org/hibernate/type/descriptor/sql/spi/DdlTypeRegistry.java b/hibernate-core/src/main/java/org/hibernate/type/descriptor/sql/spi/DdlTypeRegistry.java
index 4996977e48d7..c394864b10a4 100644
--- a/hibernate-core/src/main/java/org/hibernate/type/descriptor/sql/spi/DdlTypeRegistry.java
+++ b/hibernate-core/src/main/java/org/hibernate/type/descriptor/sql/spi/DdlTypeRegistry.java
@@ -90,12 +90,62 @@ private void addSqlType(DdlType ddlType, int sqlTypeCode) {
 		for ( String rawTypeName : ddlType.getRawTypeNames() ) {
 			final Integer previousSqlTypeCode = sqlTypes.put( rawTypeName, sqlTypeCode );
 			// Prefer the standard code over a custom code for a certain type name
-			if ( previousSqlTypeCode != null && JdbcTypeNameMapper.isStandardTypeCode( previousSqlTypeCode ) ) {
+			if ( previousSqlTypeCode != null
+				&& JdbcTypeNameMapper.isStandardTypeCode( previousSqlTypeCode )
+				&& (!JdbcTypeNameMapper.isStandardTypeCode( sqlTypeCode ) || isBigger( previousSqlTypeCode, sqlTypeCode )) ) {
 				sqlTypes.put( rawTypeName, previousSqlTypeCode );
 			}
 		}
 	}
 
+	/**
+	 * Whether {@code typeCode1} is bigger than {@code typeCode2}.
+	 * For example, a BIGINT is bigger than INTEGER, but if types are "unrelated",
+	 * e.g. VARCHAR and BIGINT, then this method will always return {@code false}.
+	 */
+	private static boolean isBigger(int typeCode1, int typeCode2) {
+		return switch ( typeCode1 ) {
+			// Integer type hierarchy: TINYINT < SMALLINT < INTEGER < BIGINT
+			case SqlTypes.BIGINT -> typeCode2 == SqlTypes.INTEGER
+					|| typeCode2 == SqlTypes.SMALLINT
+					|| typeCode2 == SqlTypes.TINYINT;
+			case SqlTypes.INTEGER -> typeCode2 == SqlTypes.SMALLINT
+					|| typeCode2 == SqlTypes.TINYINT;
+			case SqlTypes.SMALLINT -> typeCode2 == SqlTypes.TINYINT;
+			// Floating point hierarchy: REAL/FLOAT < DOUBLE
+			case SqlTypes.DOUBLE -> typeCode2 == SqlTypes.REAL
+					|| typeCode2 == SqlTypes.FLOAT;
+			// Character type hierarchy: CHAR < VARCHAR < LONG32VARCHAR < CLOB
+			case SqlTypes.CLOB -> typeCode2 == SqlTypes.LONG32VARCHAR
+					|| typeCode2 == SqlTypes.VARCHAR
+					|| typeCode2 == SqlTypes.CHAR;
+			case SqlTypes.LONG32VARCHAR -> typeCode2 == SqlTypes.VARCHAR
+					|| typeCode2 == SqlTypes.CHAR;
+			case SqlTypes.VARCHAR -> typeCode2 == SqlTypes.CHAR;
+			// National character type hierarchy: NCHAR < NVARCHAR < LONG32NVARCHAR < NCLOB
+			case SqlTypes.NCLOB -> typeCode2 == SqlTypes.LONG32NVARCHAR
+					|| typeCode2 == SqlTypes.NVARCHAR
+					|| typeCode2 == SqlTypes.NCHAR;
+			case SqlTypes.LONG32NVARCHAR -> typeCode2 == SqlTypes.NVARCHAR
+					|| typeCode2 == SqlTypes.NCHAR;
+			case SqlTypes.NVARCHAR -> typeCode2 == SqlTypes.NCHAR;
+			// Binary type hierarchy: BINARY < VARBINARY < LONG32VARBINARY < BLOB
+			case SqlTypes.BLOB -> typeCode2 == SqlTypes.LONG32VARBINARY
+					|| typeCode2 == SqlTypes.VARBINARY
+					|| typeCode2 == SqlTypes.BINARY;
+			case SqlTypes.LONG32VARBINARY -> typeCode2 == SqlTypes.VARBINARY
+					|| typeCode2 == SqlTypes.BINARY;
+			case SqlTypes.VARBINARY -> typeCode2 == SqlTypes.BINARY;
+			// Temporal type hierarchy: DATE/TIME < TIMESTAMP < TIMESTAMP_WITH_TIMEZONE
+			case SqlTypes.TIMESTAMP_WITH_TIMEZONE -> typeCode2 == SqlTypes.TIMESTAMP
+					|| typeCode2 == SqlTypes.DATE
+					|| typeCode2 == SqlTypes.TIME;
+			case SqlTypes.TIMESTAMP -> typeCode2 == SqlTypes.DATE
+					|| typeCode2 == SqlTypes.TIME;
+			default -> false;
+		};
+	}
+
 	/**
 	 * Returns the {@link SqlTypes} type code for the given DDL raw type name, or
 	 * {@code null} if the type code cannot be determined from the registrations.
diff --git a/hibernate-core/src/test/java/org/hibernate/orm/test/type/DdlTypeRegistryTest.java b/hibernate-core/src/test/java/org/hibernate/orm/test/type/DdlTypeRegistryTest.java
new file mode 100644
index 000000000000..e2e6c76fac34
--- /dev/null
+++ b/hibernate-core/src/test/java/org/hibernate/orm/test/type/DdlTypeRegistryTest.java
@@ -0,0 +1,29 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.orm.test.type;
+
+import org.hibernate.dialect.DB2Dialect;
+import org.hibernate.testing.orm.junit.Jira;
+import org.hibernate.testing.orm.junit.RequiresDialect;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.hibernate.type.SqlTypes;
+import org.hibernate.type.descriptor.sql.spi.DdlTypeRegistry;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@RequiresDialect(DB2Dialect.class)
+@SessionFactory
+public class DdlTypeRegistryTest {
+
+	@Test
+	@Jira("https://hibernate.atlassian.net/browse/HHH-20259")
+	public void testKeepBiggest(SessionFactoryScope scope) {
+		final DdlTypeRegistry ddlTypeRegistry = scope.getSessionFactory().getTypeConfiguration().getDdlTypeRegistry();
+		assertThat( ddlTypeRegistry.getSqlTypeCode( "smallint" ) ).isEqualTo( SqlTypes.SMALLINT );
+	}
+
+}