diff --git a/Makefile b/Makefile
index 4d7b1bee07..4ac51ed174 100644
--- a/Makefile
+++ b/Makefile
@@ -34,6 +34,12 @@ ifeq ($(UNAME_S),Darwin)
     PG_CONFIGURE_OPTS += --with-includes=$(OPENSSL_PREFIX)/include --with-libraries=$(OPENSSL_PREFIX)/lib
 endif
 
+# Use -C option so that when PostgreSQL "make install" installs the
+# headers, the mtime of the headers are not changed when there have
+# been no changes to the files. Changing the mtime triggers an
+# unnecessary rebuild of 'postgres_ffi'.
+PG_CONFIGURE_OPTS += INSTALL='install -C'
+
 # Choose whether we should be silent or verbose
 CARGO_BUILD_FLAGS += --$(if $(filter s,$(MAKEFLAGS)),quiet,verbose)
 # Fix for a corner case when make doesn't pass a jobserver
diff --git a/vendor/postgres-v14 b/vendor/postgres-v14
index 114676d2ed..ce723ee499 160000
--- a/vendor/postgres-v14
+++ b/vendor/postgres-v14
@@ -1 +1 @@
-Subproject commit 114676d2edd5307226d9448ec467821fdb77467d
+Subproject commit ce723ee499450cb108aede464a35a17f3d75cf84
diff --git a/vendor/postgres-v15 b/vendor/postgres-v15
index cf4db95b84..0858387047 160000
--- a/vendor/postgres-v15
+++ b/vendor/postgres-v15
@@ -1 +1 @@
-Subproject commit cf4db95b8480e08425e52ef46f78cb5a234baa0e
+Subproject commit 08583870479e30c64aeb5a97d6fee9cf470f05fb