diff --git a/tools/make/viv_preamble.mak b/tools/make/viv_preamble.mak
index 7e108e2..f7b53bf 100644
--- a/tools/make/viv_preamble.mak
+++ b/tools/make/viv_preamble.mak
@@ -29,9 +29,17 @@ HLS_IP_DIR = $(abspath $(LIB_DIR)/hls)
 
 MAKEFILE_DIR = $(abspath .)
 
-IP_BUILD_DIR ?= $(abspath ./build-ip/$(subst /,,$(PART_ID)))
 BUILD_BASE_DIR ?= $(abspath .)
 
+# -------------------------------------------------------------------
+# IP Build Directory. Call with BUILD_IP_DIR to use that as base dir.
+# -------------------------------------------------------------------
+ifdef BUILD_IP_DIR
+	IP_BUILD_DIR = $(abspath $(BUILD_IP_DIR)/$(subst /,,$(PART_ID)))
+else
+	IP_BUILD_DIR = $(abspath $(BUILD_BASE_DIR)/build-ip/$(subst /,,$(PART_ID)))
+endif
+
 # -------------------------------------------------------------------
 # Git Hash Retrieval
 # -------------------------------------------------------------------
diff --git a/top/x400/Makefile.x4xx.inc b/top/x400/Makefile.x4xx.inc
index 53a2c7d..076cc5b 100644
--- a/top/x400/Makefile.x4xx.inc
+++ b/top/x400/Makefile.x4xx.inc
@@ -171,6 +171,9 @@ IMAGE_CORE_HEADER_DEF="RFNOC_IMAGE_CORE_HDR=$(BUILD_DIR)/rfnoc_image_core.vh"
 
 VERILOG_DEFS=$(EXTRA_DEFS) $(CUSTOM_DEFS) $(GIT_HASH_VERILOG_DEF) $(IMAGE_CORE_HEADER_DEF) $(RFNOC_IMAGE_CORE_DEFS)
 
+show-var:
+	@echo "IP_BUILD_DIR: $(IP_BUILD_DIR)"
+
 # DESIGN_SRCS and VERILOG_DEFS must be defined
 bin: .prereqs
 	@echo "Build directory:: $(BUILD_DIR)"
@@ -184,7 +187,7 @@ synth: .prereqs
 rtl: .prereqs
 	$(call CHECK_VIVADO_DESIGN,$(TOOLS_DIR)/scripts/viv_check_syntax.tcl,$(TOP_MODULE),$(ARCH),$(PART_ID))
 
-viv_ip: .prereqs $$(DESIGN_SRCS) ip
+viv_ip: show-var .prereqs $$(DESIGN_SRCS) ip
 	@echo "IP build for $(NAME) DONE . . ."
 
 secure_core: .prereqs