diff --git a/fuzzers/063-gtp-common-conf/Makefile b/fuzzers/063-gtp-common-conf/Makefile
index 386d2b3f..4e939577 100644
--- a/fuzzers/063-gtp-common-conf/Makefile
+++ b/fuzzers/063-gtp-common-conf/Makefile
@@ -10,16 +10,19 @@ SHELL = bash
 
 N ?= 20
 
-SPECIMENS := $(addprefix build/specimen_,$(shell seq -f '%03.0f' $(N)))
+BUILD_DIR = build_${XRAY_PART}
+
+SPECIMENS := $(addprefix ${BUILD_DIR}/specimen_,$(shell seq -f '%03.0f' $(N)))
 SPECIMENS_OK := $(addsuffix /OK,$(SPECIMENS))
 FUZDIR ?= ${PWD}
 
+
 all: database
 
 # generate.sh / top_generate.sh call make, hence the command must
 # have a + before it.
 $(SPECIMENS_OK): $(SPECIMENS_DEPS)
-	mkdir -p build
+	mkdir -p ${BUILD_DIR}
 	bash ${XRAY_DIR}/utils/top_generate.sh $(subst /OK,,$@)
 
 run:
@@ -29,22 +32,22 @@ run:
 	touch run.${XRAY_PART}.ok
 
 clean:
-	rm -rf build run.ok
+	rm -rf ${BUILD_DIR} run.${XRAY_PART}.ok
 
 .PHONY: all run clean
 
-database: build/segbits_gtp_common.db
+database: ${BUILD_DIR}/segbits_gtp_common.db
 
-build/segbits_gtp_common.rdb: $(SPECIMENS_OK)
-	${XRAY_SEGMATCH} -o build/segbits_gtp_common.rdb $$(find $(SPECIMENS) -name "segdata_gtp_common*")
+${BUILD_DIR}/segbits_gtp_common.rdb: $(SPECIMENS_OK)
+	${XRAY_SEGMATCH} -o ${BUILD_DIR}/segbits_gtp_common.rdb $$(find $(SPECIMENS) -name "segdata_gtp_common*")
 
-build/segbits_gtp_common.db: build/segbits_gtp_common.rdb
-	${XRAY_DBFIXUP} --db-root build --zero-db bits.dbf \
-		--seg-fn-in build/segbits_gtp_common.rdb \
-		--seg-fn-out build/segbits_gtp_common.db
-	${XRAY_MASKMERGE} build/mask_gtp_common.db $$(find $(SPECIMENS) -name "segdata_gtp_common*")
+${BUILD_DIR}/segbits_gtp_common.db: ${BUILD_DIR}/segbits_gtp_common.rdb
+	${XRAY_DBFIXUP} --db-root ${BUILD_DIR} --zero-db bits.dbf \
+		--seg-fn-in ${BUILD_DIR}/segbits_gtp_common.rdb \
+		--seg-fn-out ${BUILD_DIR}/segbits_gtp_common.db
+	${XRAY_MASKMERGE} ${BUILD_DIR}/mask_gtp_common.db $$(find $(SPECIMENS) -name "segdata_gtp_common*")
 
 pushdb:
-	source pushdb.sh
+	BUILD_DIR=$(BUILD_DIR) source pushdb.sh
 
 .PHONY: database pushdb
diff --git a/fuzzers/063-gtp-common-conf/pushdb.sh b/fuzzers/063-gtp-common-conf/pushdb.sh
index 99de30dd..b9c8d743 100644
--- a/fuzzers/063-gtp-common-conf/pushdb.sh
+++ b/fuzzers/063-gtp-common-conf/pushdb.sh
@@ -7,16 +7,16 @@
 #
 # SPDX-License-Identifier: ISC
 
-if ! test $(find . -name "segdata_gtp_common_mid_right.txt" | wc -c) -eq 0
+if ! test $(find ${BUILD_DIR} -name "segdata_gtp_common_mid_right.txt" | wc -c) -eq 0
 then
-    ${XRAY_MERGEDB} gtp_common_mid_right build/segbits_gtp_common.db
-    ${XRAY_MERGEDB} mask_gtp_common_mid_right build/mask_gtp_common.db
-    ${XRAY_MERGEDB} gtp_common_mid_left build/segbits_gtp_common.db
-    ${XRAY_MERGEDB} mask_gtp_common_mid_left build/mask_gtp_common.db
+    ${XRAY_MERGEDB} gtp_common_mid_right ${BUILD_DIR}/segbits_gtp_common.db
+    ${XRAY_MERGEDB} mask_gtp_common_mid_right ${BUILD_DIR}/mask_gtp_common.db
+    ${XRAY_MERGEDB} gtp_common_mid_left ${BUILD_DIR}/segbits_gtp_common.db
+    ${XRAY_MERGEDB} mask_gtp_common_mid_left ${BUILD_DIR}/mask_gtp_common.db
 fi
 
-if ! test $(find . -name "segdata_gtp_common.txt" | wc -c) -eq 0
+if ! test $(find ${BUILD_DIR} -name "segdata_gtp_common.txt" | wc -c) -eq 0
 then
-    ${XRAY_MERGEDB} gtp_common build/segbits_gtp_common.db
-    ${XRAY_MERGEDB} mask_gtp_common build/mask_gtp_common.db
+    ${XRAY_MERGEDB} gtp_common ${BUILD_DIR}/segbits_gtp_common.db
+    ${XRAY_MERGEDB} mask_gtp_common ${BUILD_DIR}/mask_gtp_common.db
 fi