diff --git a/Makefile.PL b/Makefile.PL
index e01ca8f..ee5a5ca 100644
--- a/Makefile.PL
+++ b/Makefile.PL
@@ -230,7 +230,11 @@ unless ( $Config{usethreads} ) {
 	push @CC_DEFINE, '-DTHREADSAFE=0';
 }
 if ($^O eq 'hpux' and $Config{osvers} <= 10.20) {
-	push @CC_DEFINE, '-DSQLITE_OMIT_LOAD_EXTENSION';
+	# HP-UX 10.20 does not have pread () at all
+	push @CC_DEFINE, '-DSQLITE_OMIT_LOAD_EXTENSION',
+		'-UUSE_PREAD', '-UUSE_PREAD64',
+		'-USQLITE_ENABLE_LOCKING_STYLE',
+		'-DMAP_FAILED="((void *)-1)"';
 }
 if ($^O eq 'darwin') {
 	push @CC_DEFINE, '-DSQLITE_ENABLE_LOCKING_STYLE=0';