diff --git a/src/bin/pg_waldump/rmgrdesc.h b/src/bin/pg_waldump/rmgrdesc.h
index d5f6923e5ce..42f8483b482 100644
--- a/src/bin/pg_waldump/rmgrdesc.h
+++ b/src/bin/pg_waldump/rmgrdesc.h
@@ -8,6 +8,7 @@
 #ifndef RMGRDESC_H
 #define RMGRDESC_H
 
+#include "access/xlogreader.h"
 #include "lib/stringinfo.h"
 
 typedef struct RmgrDescData
diff --git a/src/bin/psql/crosstabview.h b/src/bin/psql/crosstabview.h
index 535ee986928..bb02032bbd5 100644
--- a/src/bin/psql/crosstabview.h
+++ b/src/bin/psql/crosstabview.h
@@ -9,6 +9,8 @@
 #ifndef CROSSTABVIEW_H
 #define CROSSTABVIEW_H
 
+#include "libpq-fe.h"
+
 /*
  * Limit the number of output columns generated in memory by the crosstabview
  * algorithm. A new output column is added for each distinct value found in the
diff --git a/src/interfaces/ecpg/ecpglib/ecpglib_extern.h b/src/interfaces/ecpg/ecpglib/ecpglib_extern.h
index f9336a0c23d..6cb7ab1a192 100644
--- a/src/interfaces/ecpg/ecpglib/ecpglib_extern.h
+++ b/src/interfaces/ecpg/ecpglib/ecpglib_extern.h
@@ -8,6 +8,7 @@
 #include "sqlda-native.h"
 #include "sqlda-compat.h"
 #include "ecpg_config.h"
+#include "ecpgtype.h"
 
 #ifndef CHAR_BIT
 #include <limits.h>
diff --git a/src/interfaces/ecpg/test/printf_hack.h b/src/interfaces/ecpg/test/printf_hack.h
index ef584c0d548..1c061d5e87e 100644
--- a/src/interfaces/ecpg/test/printf_hack.h
+++ b/src/interfaces/ecpg/test/printf_hack.h
@@ -2,7 +2,7 @@
  * print_double(x) has the same effect as printf("%g", x), but is intended
  * to produce the same formatting across all platforms.
  */
-static void
+static inline void
 print_double(double x)
 {
 #ifdef WIN32
diff --git a/src/interfaces/libpq/fe-gssapi-common.h b/src/interfaces/libpq/fe-gssapi-common.h
index deb010e4066..ebe24f7ca01 100644
--- a/src/interfaces/libpq/fe-gssapi-common.h
+++ b/src/interfaces/libpq/fe-gssapi-common.h
@@ -16,8 +16,13 @@
 #include "libpq-fe.h"
 #include "libpq-int.h"
 
+#ifdef ENABLE_GSS
+
 void		pg_GSS_error(const char *mprefix, PGconn *conn,
 						 OM_uint32 maj_stat, OM_uint32 min_stat);
 bool		pg_GSS_have_ccache(gss_cred_id_t *cred_out);
 int			pg_GSS_load_servicename(PGconn *conn);
+
+#endif
+
 #endif							/* FE_GSSAPI_COMMON_H */
diff --git a/src/pl/plperl/plperl_helpers.h b/src/pl/plperl/plperl_helpers.h
index 65b85a27aed..1e318b6dc83 100644
--- a/src/pl/plperl/plperl_helpers.h
+++ b/src/pl/plperl/plperl_helpers.h
@@ -3,6 +3,9 @@
 
 #include "mb/pg_wchar.h"
 
+#include "plperl.h"
+
+
 /*
  * convert from utf8 to database encoding
  *
diff --git a/src/pl/plpython/plpy_elog.h b/src/pl/plpython/plpy_elog.h
index 967df784652..e02ef4ffe9f 100644
--- a/src/pl/plpython/plpy_elog.h
+++ b/src/pl/plpython/plpy_elog.h
@@ -5,6 +5,8 @@
 #ifndef PLPY_ELOG_H
 #define PLPY_ELOG_H
 
+#include "plpython.h"
+
 /* global exception classes */
 extern PyObject *PLy_exc_error;
 extern PyObject *PLy_exc_fatal;
diff --git a/src/pl/plpython/plpy_resultobject.h b/src/pl/plpython/plpy_resultobject.h
index bbaca0dd00f..978c4cc176c 100644
--- a/src/pl/plpython/plpy_resultobject.h
+++ b/src/pl/plpython/plpy_resultobject.h
@@ -7,6 +7,8 @@
 
 #include "access/tupdesc.h"
 
+#include "plpython.h"
+
 
 typedef struct PLyResultObject
 {
diff --git a/src/pl/plpython/plpy_spi.h b/src/pl/plpython/plpy_spi.h
index 5a0eef78dcd..ec7b6893597 100644
--- a/src/pl/plpython/plpy_spi.h
+++ b/src/pl/plpython/plpy_spi.h
@@ -7,6 +7,8 @@
 
 #include "utils/resowner.h"
 
+#include "plpython.h"
+
 extern PyObject *PLy_spi_prepare(PyObject *self, PyObject *args);
 extern PyObject *PLy_spi_execute(PyObject *self, PyObject *args);
 extern PyObject *PLy_spi_execute_plan(PyObject *ob, PyObject *list, long limit);
diff --git a/src/pl/plpython/plpy_subxactobject.h b/src/pl/plpython/plpy_subxactobject.h
index 92a9e635f3a..1ee85c0cdf3 100644
--- a/src/pl/plpython/plpy_subxactobject.h
+++ b/src/pl/plpython/plpy_subxactobject.h
@@ -8,6 +8,8 @@
 #include "nodes/pg_list.h"
 #include "utils/resowner.h"
 
+#include "plpython.h"
+
 /* a list of nested explicit subtransactions */
 extern List *explicit_subtransactions;
 
diff --git a/src/pl/plpython/plpy_typeio.h b/src/pl/plpython/plpy_typeio.h
index 64c72fa4785..3412a9817bf 100644
--- a/src/pl/plpython/plpy_typeio.h
+++ b/src/pl/plpython/plpy_typeio.h
@@ -9,6 +9,8 @@
 #include "fmgr.h"
 #include "utils/typcache.h"
 
+#include "plpython.h"
+
 struct PLyProcedure;			/* avoid requiring plpy_procedure.h here */
 
 
diff --git a/src/pl/plpython/plpy_util.h b/src/pl/plpython/plpy_util.h
index f990bb08908..c9ba7edc0ec 100644
--- a/src/pl/plpython/plpy_util.h
+++ b/src/pl/plpython/plpy_util.h
@@ -6,6 +6,8 @@
 #ifndef PLPY_UTIL_H
 #define PLPY_UTIL_H
 
+#include "plpython.h"
+
 extern PyObject *PLyUnicode_Bytes(PyObject *unicode);
 extern char *PLyUnicode_AsString(PyObject *unicode);
 
diff --git a/src/pl/plpython/plpython.h b/src/pl/plpython/plpython.h
index 1a9463a1e31..3a1f0d56d7c 100644
--- a/src/pl/plpython/plpython.h
+++ b/src/pl/plpython/plpython.h
@@ -14,7 +14,8 @@
 
 /*
  * Include order should be: postgres.h, other postgres headers, plpython.h,
- * other plpython headers
+ * other plpython headers.  (In practice, other plpython headers will also
+ * include this file, so that they can compile standalone.)
  */
 #ifndef POSTGRES_H
 #error postgres.h must be included before plpython.h