diff --git a/Makefile.work b/Makefile.work
index 21e40fb633..0fde2e3893 100644
--- a/Makefile.work
+++ b/Makefile.work
@@ -568,6 +568,7 @@ SONIC_BUILD_INSTRUCTION :=  $(MAKE) \
                            GZ_COMPRESS_PROGRAM=$(GZ_COMPRESS_PROGRAM) \
                            MIRROR_SNAPSHOT=$(MIRROR_SNAPSHOT) \
                            SONIC_VERSION_CONTROL_COMPONENTS=$(SONIC_VERSION_CONTROL_COMPONENTS) \
+                           ONIE_IMAGE_PART_SIZE=$(ONIE_IMAGE_PART_SIZE) \
                            SONIC_OS_VERSION=$(SONIC_OS_VERSION) \
                            $(SONIC_OVERRIDE_BUILD_VARS)
 
diff --git a/installer/install.sh b/installer/install.sh
index 7f3feae42b..4d8ad75a16 100755
--- a/installer/install.sh
+++ b/installer/install.sh
@@ -96,6 +96,13 @@ echo "onie_platform: $onie_platform"
 # Get platform specific linux kernel command line arguments
 ONIE_PLATFORM_EXTRA_CMDLINE_LINUX=""
 
+# Start with build time value, set either using env variable
+# or from onie-image.conf. onie-mk-demo.sh will string replace
+# below value to env value. Platform specific installer.conf
+# will override this value if necessary by reading $onie_platform
+# after this.
+ONIE_IMAGE_PART_SIZE="%%ONIE_IMAGE_PART_SIZE%%"
+
 # Default var/log device size in MB
 VAR_LOG_SIZE=4096
 
@@ -138,9 +145,8 @@ fi
 # with "OS" or "DIAG".
 demo_type="%%DEMO_TYPE%%"
 
-# The build system prepares this script by replacing %%ONIE_IMAGE_PART_SIZE%%
-# with the partition size
-demo_part_size="%%ONIE_IMAGE_PART_SIZE%%"
+# take final partition size after platform installer.conf override
+demo_part_size=$ONIE_IMAGE_PART_SIZE
 
 # The build system prepares this script by replacing %%IMAGE_VERSION%%
 # with git revision hash as a version identifier
diff --git a/slave.mk b/slave.mk
index ae4e6171c8..6a51dc6ae9 100644
--- a/slave.mk
+++ b/slave.mk
@@ -384,6 +384,7 @@ $(info "SECURE_UPGRADE_DEV_SIGNING_KEY"  : "$(SECURE_UPGRADE_DEV_SIGNING_KEY)")
 $(info "SECURE_UPGRADE_SIGNING_CERT" : "$(SECURE_UPGRADE_SIGNING_CERT)")
 $(info "SECURE_UPGRADE_PROD_SIGNING_TOOL": "$(SECURE_UPGRADE_PROD_SIGNING_TOOL)")
 $(info "SECURE_UPGRADE_PROD_TOOL_ARGS"   : "$(SECURE_UPGRADE_PROD_TOOL_ARGS)")
+$(info "ONIE_IMAGE_PART_SIZE"            : "$(ONIE_IMAGE_PART_SIZE)")
 $(info "ENABLE_DHCP_GRAPH_SERVICE"       : "$(ENABLE_DHCP_GRAPH_SERVICE)")
 $(info "SHUTDOWN_BGP_ON_START"           : "$(SHUTDOWN_BGP_ON_START)")
 $(info "ENABLE_PFCWD_ON_START"           : "$(ENABLE_PFCWD_ON_START)")
@@ -1435,6 +1436,7 @@ $(addprefix $(TARGET_PATH)/, $(SONIC_INSTALLERS)) : $(TARGET_PATH)/% : \
 		TARGET_MACHINE=$(dep_machine) \
 		IMAGE_TYPE=$($*_IMAGE_TYPE) \
 		TARGET_PATH=$(TARGET_PATH) \
+		ONIE_IMAGE_PART_SIZE=$(ONIE_IMAGE_PART_SIZE) \
 		SONIC_ENFORCE_VERSIONS=$(SONIC_ENFORCE_VERSIONS) \
 		TRUSTED_GPG_URLS=$(TRUSTED_GPG_URLS) \
 		SONIC_ENABLE_SECUREBOOT_SIGNATURE="$(SONIC_ENABLE_SECUREBOOT_SIGNATURE)" \
@@ -1462,6 +1464,7 @@ $(addprefix $(TARGET_PATH)/, $(SONIC_INSTALLERS)) : $(TARGET_PATH)/% : \
 		PASSWORD="$(PASSWORD)" \
 		TARGET_MACHINE=$(dep_machine) \
 		IMAGE_TYPE=$($*_IMAGE_TYPE) \
+		ONIE_IMAGE_PART_SIZE=$(ONIE_IMAGE_PART_SIZE) \
 		SONIC_ENABLE_IMAGE_SIGNATURE="$(SONIC_ENABLE_IMAGE_SIGNATURE)" \
 		SECURE_UPGRADE_MODE="$(SECURE_UPGRADE_MODE)" \
 		SECURE_UPGRADE_DEV_SIGNING_KEY="$(SECURE_UPGRADE_DEV_SIGNING_KEY)" \