diff --git a/src/soc/amd/cezanne/Makefile.inc b/src/soc/amd/cezanne/Makefile.inc
index 46ac199649..ef099de593 100644
--- a/src/soc/amd/cezanne/Makefile.inc
+++ b/src/soc/amd/cezanne/Makefile.inc
@@ -45,6 +45,9 @@ MAINBOARD_BLOBS_DIR:=$(top)/3rdparty/blobs/mainboard/$(MAINBOARDDIR)
 # |           |  PSPDIR ADDR  |  BIOSDIR ADDR  |
 # +-----------+---------------+----------------+
 
+$(if $(CONFIG_AMD_FWM_POSITION_INDEX), ,\
+     $(error Invalid AMD firmware position index. Check if the board sets a valid ROM size))
+
 CEZANNE_FWM_POSITION=$(call int-add, \
 	$(call int-subtract, 0xffffffff \
 	$(call int-shift-left, \
diff --git a/src/soc/amd/picasso/Makefile.inc b/src/soc/amd/picasso/Makefile.inc
index 5dac1f6950..5152d4713a 100644
--- a/src/soc/amd/picasso/Makefile.inc
+++ b/src/soc/amd/picasso/Makefile.inc
@@ -84,6 +84,9 @@ MAINBOARD_BLOBS_DIR:=$(top)/3rdparty/blobs/mainboard/$(MAINBOARDDIR)
 # |           |  PSPDIR ADDR  |  BIOSDIR ADDR  |
 # +-----------+---------------+----------------+
 
+$(if $(CONFIG_AMD_FWM_POSITION_INDEX), ,\
+     $(error Invalid AMD firmware position index. Check if the board sets a valid ROM size))
+
 PICASSO_FWM_POSITION=$(call int-add, \
 	$(call int-subtract, 0xffffffff \
 	$(call int-shift-left, \