diff --git a/target/linux/brcm63xx/image/bcm63xx.mk b/target/linux/brcm63xx/image/bcm63xx.mk
index 34d496e928..ce03f7b700 100644
--- a/target/linux/brcm63xx/image/bcm63xx.mk
+++ b/target/linux/brcm63xx/image/bcm63xx.mk
@@ -922,7 +922,7 @@ define Device/NEUFBOX4-SER
   DEVICE_DTS := nb4-ser-r0
   CFE_BOARD_ID := 96358VW
   CFE_CHIP_ID := 6358
-  CFE_EXTRAS += --rsa-signature "LEDE-$(REVISION)"
+  CFE_EXTRAS += --rsa-signature "LEDE-$(firstword $(subst -,$(space),$(REVISION)))"
   DEVICE_PACKAGES := \
     $(B43_PACKAGES) $(USB2_PACKAGES)
 endef
@@ -934,7 +934,7 @@ define Device/NEUFBOX4-FXC
   DEVICE_DTS := nb4-fxc-r1
   CFE_BOARD_ID := 96358VW
   CFE_CHIP_ID := 6358
-  CFE_EXTRAS += --rsa-signature "LEDE-$(REVISION)"
+  CFE_EXTRAS += --rsa-signature "LEDE-$(firstword $(subst -,$(space),$(REVISION)))"
   DEVICE_PACKAGES := \
     $(B43_PACKAGES) $(USB2_PACKAGES)
 endef
@@ -946,7 +946,7 @@ define Device/NEUFBOX6
   DEVICE_DTS := nb6-ser-r0
   CFE_BOARD_ID := NB6-SER-r0
   CFE_CHIP_ID := 6362
-  CFE_EXTRAS += --rsa-signature "LEDE-$(REVISION)"
+  CFE_EXTRAS += --rsa-signature "LEDE-$(firstword $(subst -,$(space),$(REVISION)))"
   DEVICE_PACKAGES := \
     $(B43_PACKAGES) $(USB2_PACKAGES)
 endef