diff --git a/CHANGELOG.md b/CHANGELOG.md
index e3ae27cb..63c8ada6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,8 +20,9 @@ avoid adding features or APIs which do not map onto the
 
 ## [Unreleased]
 
-## [4.5.0] - 2026-06-08
+- Use `PG_MODULE_MAGIC_EXT` macro in PostgreSQL 18 and later ([#203], [Andreas Karlsson])
 
+## [4.5.0] - 2026-06-08
 
 ### Project
 
@@ -356,7 +357,9 @@ avoid adding features or APIs which do not map onto the
 [#192]: https://github.com/postgis/h3-pg/issues/192
 [#194]: https://github.com/postgis/h3-pg/pull/194
 [#197]: https://github.com/postgis/h3-pg/pull/197
+[#203]: https://github.com/postgis/h3-pg/pull/203
 [Abel Vázquez Montoro]: https://github.com/AbelVM
+[Andreas Karlsson]: https://github.com/jeltz
 [Darafei Praliaskouski]: https://github.com/Komzpa
 [Eric Schoffstall]: https://github.com/yocontra
 [Paul Ramsey]: https://github.com/pramsey
diff --git a/h3/src/init.c b/h3/src/init.c
index 1cd9700e..8f4940af 100644
--- a/h3/src/init.c
+++ b/h3/src/init.c
@@ -21,10 +21,15 @@
 
 #include <fmgr.h> // PG_MODULE_MAGIC
 
+#include "config.h"
 #include "guc.h"
 
 /* see https://www.postgresql.org/docs/current/xfunc-c.html#XFUNC-C-DYNLOAD */
+#if POSTGRESQL_VERSION_MAJOR >= 18
+PG_MODULE_MAGIC_EXT(.name = "h3", .version = POSTGRESQL_H3_VERSION);
+#else
 PG_MODULE_MAGIC;
+#endif
 
 void
 _PG_init(void)
diff --git a/h3_postgis/CMakeLists.txt b/h3_postgis/CMakeLists.txt
index 0ec8e22f..855ec635 100644
--- a/h3_postgis/CMakeLists.txt
+++ b/h3_postgis/CMakeLists.txt
@@ -45,6 +45,15 @@ PostgreSQL_add_extension(postgresql_h3_postgis
     sql/updates/h3_postgis--4.5.0--unreleased.sql
 )
 
+# configure
+configure_file(src/config.h.in src/config.h)
+
+# include
+target_include_directories(postgresql_h3_postgis PRIVATE
+  ${CMAKE_CURRENT_BINARY_DIR}/src
+  src
+)
+
 # link
 target_link_libraries(postgresql_h3_postgis PRIVATE postgresql_h3_shared h3)
 target_include_directories(postgresql_h3_postgis PRIVATE ${H3_INTERNAL_INCLUDE_DIR})
diff --git a/h3_postgis/src/config.h.in b/h3_postgis/src/config.h.in
new file mode 100644
index 00000000..fb4bb002
--- /dev/null
+++ b/h3_postgis/src/config.h.in
@@ -0,0 +1,22 @@
+/*
+ * Copyright 2026 Andreas Karlsson
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *	   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef PGH3_CONFIG_H
+#define PGH3_CONFIG_H
+
+#define POSTGRESQL_PGH3_VERSION "@INSTALL_VERSION@"
+
+#endif /* PGH3_CONFIG_H */
diff --git a/h3_postgis/src/init.c b/h3_postgis/src/init.c
index a41447d3..b1a6676e 100644
--- a/h3_postgis/src/init.c
+++ b/h3_postgis/src/init.c
@@ -18,5 +18,11 @@
 
 #include <fmgr.h> // PG_MODULE_MAGIC
 
+#include "config.h"
+
 /* see https://www.postgresql.org/docs/current/xfunc-c.html#XFUNC-C-DYNLOAD */
+#if POSTGRESQL_VERSION_MAJOR >= 18
+PG_MODULE_MAGIC_EXT(.name = "h3_postgis", .version = POSTGRESQL_PGH3_VERSION);
+#else
 PG_MODULE_MAGIC;
+#endif