diff --git a/src/test/isolation/Makefile b/src/test/isolation/Makefile
index 0f709a1e3c2..c027c29ab76 100644
--- a/src/test/isolation/Makefile
+++ b/src/test/isolation/Makefile
@@ -10,7 +10,7 @@ ifeq ($(PORTNAME), win32)
 LDLIBS += -lws2_32
 endif
 
-override CPPFLAGS := -I$(srcdir) -I$(libpq_srcdir) $(CPPFLAGS)
+override CPPFLAGS := -I$(srcdir) -I$(libpq_srcdir) -I$(srcdir)/../regress $(CPPFLAGS)
 override LDLIBS := $(libpq_pgport) $(LDLIBS)
 
 OBJS =  specparse.o isolationtester.o
@@ -64,7 +64,7 @@ endif
 clean distclean:
 	rm -f isolationtester$(X) pg_isolation_regress$(X) $(OBJS) isolation_main.o
 	rm -f pg_regress.o
-	rm -rf results
+	rm -rf $(pg_regress_clean_files)
 
 maintainer-clean: distclean
 	rm -f specparse.c specscanner.c
diff --git a/src/test/isolation/isolation_main.c b/src/test/isolation/isolation_main.c
index 2df12f879e4..18cd8ef7fdb 100644
--- a/src/test/isolation/isolation_main.c
+++ b/src/test/isolation/isolation_main.c
@@ -10,7 +10,7 @@
  *-------------------------------------------------------------------------
  */
 
-#include "../regress/pg_regress.h"
+#include "pg_regress.h"
 
 /*
  * start an isolation tester process for specified file (including
diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c
index 44a4858c96c..0f77917fb53 100644
--- a/src/test/isolation/isolationtester.c
+++ b/src/test/isolation/isolationtester.c
@@ -5,14 +5,12 @@
  *		Runs an isolation test specified by a spec file.
  */
 
+#include "postgres_fe.h"
+
 #ifdef WIN32
 #include <windows.h>
 #endif
 
-#include <stddef.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
 #include "libpq-fe.h"
 
 #include "isolationtester.h"
diff --git a/src/test/isolation/specparse.y b/src/test/isolation/specparse.y
index c6847802163..47bfbc4f399 100644
--- a/src/test/isolation/specparse.y
+++ b/src/test/isolation/specparse.y
@@ -10,10 +10,7 @@
  *-------------------------------------------------------------------------
  */
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <stdint.h>
-#include <string.h>
+#include "postgres_fe.h"
 
 #include "isolationtester.h"