diff --git a/src/interfaces/ecpg/test/preproc/strings.pgc b/src/interfaces/ecpg/test/preproc/strings.pgc
index 7d85362607..d6ec9a4cb8 100644
--- a/src/interfaces/ecpg/test/preproc/strings.pgc
+++ b/src/interfaces/ecpg/test/preproc/strings.pgc
@@ -1,7 +1,7 @@
-#include "../regression.h"
+#include <../regression.h>
 
 exec sql begin declare section;
-#include "strings.h"
+#include <strings.h>
 exec sql end declare section;
 
 int main(void)