diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1a0529c6a..3bd8315d8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -31,6 +31,20 @@ ecbuild_requires_macro_version( 2.7.2 )
 
 ecbuild_declare_project()
 
+###############################################################################
+# system checks needed for eccodes_config.h and some options like MEMFS
+
+check_include_files( assert.h         ECCODES_HAVE_ASSERT_H      )
+check_include_files( string.h         ECCODES_HAVE_STRING_H      )
+check_include_files( sys/types.h      ECCODES_HAVE_SYS_TYPES_H   )
+check_include_files( sys/stat.h       ECCODES_HAVE_SYS_STAT_H    )
+check_include_files( fcntl.h          ECCODES_HAVE_FCNTL_H      )
+check_include_files( unistd.h         ECCODES_HAVE_UNISTD_H      )
+check_symbol_exists( fseeko           "stdio.h"    ECCODES_HAVE_FSEEKO )
+check_symbol_exists( posix_memalign   "stdlib.h"   ECCODES_HAVE_POSIX_MEMALIGN )
+check_symbol_exists( fmemopen         "stdio.h"    ECCODES_HAVE_FMEMOPEN )
+check_symbol_exists( funopen          "stdio.h"    ECCODES_HAVE_FUNOPEN )
+
 ###############################################################################
 # some variables/options of this project
 
@@ -96,7 +110,7 @@ endif()
 ecbuild_add_option( FEATURE MEMFS
     DESCRIPTION "Memory based access to definitions/samples"
     DEFAULT OFF
-    CONDITION EC_HAVE_FMEMOPEN OR EC_HAVE_FUNOPEN
+    CONDITION ECCODES_HAVE_FMEMOPEN OR ECCODES_HAVE_FUNOPEN
     REQUIRED_PACKAGES PythonInterp
 )
 
@@ -276,25 +290,6 @@ set( ECCODES_IFS_SAMPLES_PATH ${the_default_data_prefix}/${ECCODES_IFS_SAMPLES_S
 ###############################################################################
 ### config header
 
-# system checks needed for eccodes_config.h
-
-ecbuild_cache_check_include_files( assert.h       EC_HAVE_ASSERT_H      )
-
-ecbuild_cache_check_include_files( string.h       EC_HAVE_STRING_H      )
-
-ecbuild_cache_check_symbol_exists( fseeko "stdio.h" EC_HAVE_FSEEKO )
-
-ecbuild_cache_check_include_files( sys/types.h    EC_HAVE_SYS_TYPES_H   )
-
-ecbuild_cache_check_include_files( sys/stat.h     EC_HAVE_SYS_STAT_H    )
-
-ecbuild_cache_check_include_files( fcntl.h        EC_HAVE_FCNTL_H      )
-
-ecbuild_cache_check_include_files( unistd.h       EC_HAVE_UNISTD_H      )
-
-ecbuild_cache_check_symbol_exists( posix_memalign "stdlib.h" EC_HAVE_POSIX_MEMALIGN )
-
-
 ecbuild_generate_config_headers()
 
 configure_file( eccodes_config.h.in eccodes_config.h )
diff --git a/eccodes_config.h.in b/eccodes_config.h.in
index 4b14f898f..7e3464fad 100644
--- a/eccodes_config.h.in
+++ b/eccodes_config.h.in
@@ -40,35 +40,46 @@
 
 /* headers */
 
-#ifdef EC_HAVE_ASSERT_H
+#cmakedefine ECCODES_HAVE_ASSERT_H
+#cmakedefine ECCODES_HAVE_STRING_H
+#cmakedefine ECCODES_HAVE_SYS_TYPES_H
+#cmakedefine ECCODES_HAVE_SYS_STAT_H
+#cmakedefine ECCODES_HAVE_FCNTL_H
+#cmakedefine ECCODES_HAVE_UNISTD_H
+#cmakedefine ECCODES_HAVE_FSEEKO
+#cmakedefine ECCODES_HAVE_POSIX_MEMALIGN
+#cmakedefine ECCODES_HAVE_FMEMOPEN
+#cmakedefine ECCODES_HAVE_FUNOPEN
+
+#if defined(EC_HAVE_ASSERT_H) || defined(ECCODES_HAVE_ASSERT_H)
 #define   HAVE_ASSERT_H 1
 #endif
 
-#ifdef EC_HAVE_STRING_H
+#if defined(EC_HAVE_STRING_H) || defined(ECCODES_HAVE_STRING_H)
 #define   HAVE_STRING_H 1
 #endif
 
-#ifdef EC_HAVE_FSEEKO
-#define   HAVE_FSEEKO 1
-#endif
-
-#ifdef EC_HAVE_SYS_TYPES_H
+#if defined(EC_HAVE_SYS_TYPES_H) || defined(ECCODES_HAVE_SYS_TYPES_H)
 #define   HAVE_SYS_TYPES_H 1
 #endif
 
-#ifdef  EC_HAVE_SYS_STAT_H
+#if defined(EC_HAVE_SYS_STAT_H) || defined(ECCODES_HAVE_SYS_STAT_H)
 #define    HAVE_SYS_STAT_H 1
 #endif
 
-#ifdef  EC_HAVE_FCNTL_H
+#if defined(EC_HAVE_FCNTL_H) || defined(ECCODES_HAVE_FCNTL_H)
 #define    HAVE_FCNTL_H 1
 #endif
 
-#ifdef  EC_HAVE_UNISTD_H
+#if defined(EC_HAVE_UNISTD_H) || defined(ECCODES_HAVE_UNISTD_H)
 #define    HAVE_UNISTD_H 1
 #endif
 
-#ifdef  EC_HAVE_POSIX_MEMALIGN
+#if defined(EC_HAVE_FSEEKO) || defined(ECCODES_HAVE_FSEEKO)
+#define   HAVE_FSEEKO 1
+#endif
+
+#if defined(EC_HAVE_POSIX_MEMALIGN) || defined(ECCODES_HAVE_POSIX_MEMALIGN)
 #define         POSIX_MEMALIGN 1
 #endif
 
diff --git a/memfs.py b/memfs.py
index 784d09e22..d5ae99461 100755
--- a/memfs.py
+++ b/memfs.py
@@ -76,7 +76,7 @@ for directory in dirs:
 
 print("""
 #include "eccodes_config.h"
-#ifdef EC_HAVE_FMEMOPEN
+#ifdef ECCODES_HAVE_FMEMOPEN
 #define _GNU_SOURCE
 #endif
 
@@ -99,7 +99,7 @@ for k, v in sorted(items):
 
 print("""};
 
-#if defined(EC_HAVE_FUNOPEN) && !defined(EC_HAVE_FMEMOPEN)
+#if defined(ECCODES_HAVE_FUNOPEN) && !defined(ECCODES_HAVE_FMEMOPEN)
 
 typedef struct mem_file {
     const char* buffer;