diff --git a/cpu/stm32/Makefile.include b/cpu/stm32/Makefile.include
index 7259e63ba2..151696a9bd 100644
--- a/cpu/stm32/Makefile.include
+++ b/cpu/stm32/Makefile.include
@@ -13,13 +13,20 @@ ROM_LEN_K := $(shell echo $(ROM_LEN) | sed 's/K//')
 RAM_LEN_K := $(shell echo $(RAM_LEN) | sed 's/K//')
 
 ifneq (,$(filter w%,$(CPU_FAM)))
-  # adjust RAM_LEN and ROM_LEN according to CPU2 RAM_LEN and ROM_LEN
-  CPU2_RAM_LEN_K := $(shell echo $(CPU2_RAM_LEN) | sed 's/K//')
-  RAM_LEN := $(shell echo $$(( ($(RAM_LEN_K) - $(CPU2_RAM_LEN_K) ) * $(KB) )))
-
-  CPU2_ROM_LEN_K := $(shell echo $(CPU2_ROM_LEN) | sed 's/K//')
-  FLASHSIZE := $(shell echo $$(( ($(ROM_LEN_K) - $(CPU2_ROM_LEN_K) )* $(KB) )) )
-  ROM_LEN := $(shell echo $$(( ($(ROM_LEN_K) - $(CPU2_ROM_LEN_K) ) ))K)
+  ifneq (,$(CPU2_RAM_LEN))
+    # adjust RAM_LEN and ROM_LEN according to CPU2 RAM_LEN and ROM_LEN
+    CPU2_RAM_LEN_K := $(shell echo $(CPU2_RAM_LEN) | sed 's/K//')
+    RAM_LEN := $(shell echo $$(( ($(RAM_LEN_K) - $(CPU2_RAM_LEN_K) ) * $(KB) )))
+  else
+    RAM_LEN := $(shell echo $$(( $(RAM_LEN_K) * $(KB) )) )
+  endif
+  ifneq (,$(CPU2_ROM_LEN))
+    CPU2_ROM_LEN_K := $(shell echo $(CPU2_ROM_LEN) | sed 's/K//')
+    FLASHSIZE := $(shell echo $$(( ($(ROM_LEN_K) - $(CPU2_ROM_LEN_K) )* $(KB) )) )
+    ROM_LEN := $(shell echo $$(( ($(ROM_LEN_K) - $(CPU2_ROM_LEN_K) ) ))K)
+  else
+    FLASHSIZE := $(shell echo $$(( $(ROM_LEN_K) * $(KB) )) )
+  endif
 else
   FLASHSIZE := $(shell echo $$(( $(ROM_LEN_K) * $(KB) )) )
   RAM_LEN := $(shell echo $$(( $(RAM_LEN_K) * $(KB) )) )
diff --git a/cpu/stm32/periph/flashpage.c b/cpu/stm32/periph/flashpage.c
index 2a56276457..4a559167a0 100644
--- a/cpu/stm32/periph/flashpage.c
+++ b/cpu/stm32/periph/flashpage.c
@@ -190,7 +190,8 @@ void flashpage_erase(unsigned page)
     assert(page < (int)FLASHPAGE_NUMOF);
 
     /* ensure there is no attempt to write to CPU2 protected area */
-#if defined(CPU_FAM_STM32WB) || defined(CPU_FAM_STM32WL)
+#if defined(CPU_FAM_STM32WB) || (defined(CPU_FAM_STM32WL) && \
+                                 !defined(CPU_LINE_STM32WLE5xx))
     assert(page < (int)(FLASH->SFR & FLASH_SFR_SFSA));
 #endif
 
diff --git a/drivers/periph_common/flashpage.c b/drivers/periph_common/flashpage.c
index cb8e8b1967..f9457c213f 100644
--- a/drivers/periph_common/flashpage.c
+++ b/drivers/periph_common/flashpage.c
@@ -33,7 +33,8 @@ void flashpage_read(unsigned page, void *data)
 {
     assert(page < FLASHPAGE_NUMOF);
 
-#if defined(CPU_FAM_STM32WB) || defined(CPU_FAM_STM32WL)
+#if defined(CPU_FAM_STM32WB) || (defined(CPU_FAM_STM32WL) && \
+                                 !defined(CPU_LINE_STM32WLE5xx))
     assert(page < (FLASH->SFR & FLASH_SFR_SFSA));
 #endif
 
@@ -44,7 +45,8 @@ int flashpage_verify(unsigned page, const void *data)
 {
     assert(page < (int)FLASHPAGE_NUMOF);
 
-#if defined(CPU_FAM_STM32WB) || defined(CPU_FAM_STM32WL)
+#if defined(CPU_FAM_STM32WB) || (defined(CPU_FAM_STM32WL) && \
+                                 !defined(CPU_LINE_STM32WLE5xx))
     assert(page < (int)(FLASH->SFR & FLASH_SFR_SFSA));
 #endif