diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 193620da12..ec8a3a8fb1 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -191,6 +191,7 @@ stages:
   stage: build
   before_script:
     - test -w "${CCACHE_DIR}" && export PATH="/usr/lib/ccache:${PATH}"
+    - test -n "${OOT_BUILD_WORKSPACE}" && mkdir "${OOT_BUILD_WORKSPACE}" && cd "${OOT_BUILD_WORKSPACE}"
   script:
     - *configure
     - ${MAKE} -j${BUILD_PARALLEL_JOBS:-1} -k all V=1
@@ -658,6 +659,19 @@ cppcheck:gcc:sid:amd64:
     - gcc:sid:amd64
   needs: ["gcc:sid:amd64"]
 
+# Job for out-of-tree GCC build on Debian Sid (amd64)
+
+oot:sid:amd64:
+  variables:
+    CC: gcc
+    CFLAGS: "${CFLAGS_COMMON} -O3"
+    CONFIGURE: ../configure
+    EXTRA_CONFIGURE: "--enable-dnstap --with-libidn2"
+    RUN_MAKE_INSTALL: 1
+    OOT_BUILD_WORKSPACE: workspace
+  <<: *debian_sid_amd64_image
+  <<: *build_job
+
 # Jobs for tarball GCC builds on Debian Sid (amd64)
 
 tarball:sid:amd64:
diff --git a/lib/isc/netmgr/Makefile.in b/lib/isc/netmgr/Makefile.in
index d931b7c26d..74f0439521 100644
--- a/lib/isc/netmgr/Makefile.in
+++ b/lib/isc/netmgr/Makefile.in
@@ -11,9 +11,11 @@ srcdir =	@srcdir@
 VPATH =		@srcdir@
 top_srcdir =	@top_srcdir@
 
-CINCLUDES =	-I${srcdir}/../include \
+CINCLUDES =	-I${srcdir}/include \
 		-I${srcdir}/../unix/include \
 		-I${srcdir}/../pthreads/include \
+		-I../include \
+		-I${srcdir}/../include \
 		-I${srcdir}/.. \
 		${OPENSSL_CFLAGS} \
 		${JSON_C_CFLAGS} \
diff --git a/lib/isc/netmgr/uverr2result.c b/lib/isc/netmgr/uverr2result.c
index 09a3d6ecd0..d3f95a3a09 100644
--- a/lib/isc/netmgr/uverr2result.c
+++ b/lib/isc/netmgr/uverr2result.c
@@ -12,7 +12,6 @@
 #include <stdbool.h>
 #include <uv.h>
 
-#include <isc/platform.h>
 #include <isc/result.h>
 #include <isc/strerr.h>
 #include <isc/string.h>