diff --git a/src/flash/nor/stm32f1x.c b/src/flash/nor/stm32f1x.c
index 938785ef1..b6359a0a8 100644
--- a/src/flash/nor/stm32f1x.c
+++ b/src/flash/nor/stm32f1x.c
@@ -902,6 +902,11 @@ static int stm32x_probe(struct flash_bank *bank)
 		flash_size_in_kb = 0xffff;
 	}
 
+	/* some variants read 0 for flash size register
+	 * use a max flash size as a default */
+	if (flash_size_in_kb == 0)
+		flash_size_in_kb = 0xffff;
+
 	if ((device_id & 0xfff) == 0x410) {
 		/* medium density - we have 1k pages
 		 * 4 pages for a protection area */
diff --git a/src/flash/nor/stm32f2x.c b/src/flash/nor/stm32f2x.c
index c7e050d0d..5f5bfb853 100644
--- a/src/flash/nor/stm32f2x.c
+++ b/src/flash/nor/stm32f2x.c
@@ -605,6 +605,11 @@ static int stm32x_probe(struct flash_bank *bank)
 		flash_size_in_kb = 0xffff;
 	}
 
+	/* some variants read 0 for flash size register
+	 * use a max flash size as a default */
+	if (flash_size_in_kb == 0)
+		flash_size_in_kb = 0xffff;
+
 	if ((device_id & 0xfff) == 0x411) {
 		/* check for early silicon */
 		if (flash_size_in_kb == 0xffff) {
diff --git a/src/flash/nor/stm32lx.c b/src/flash/nor/stm32lx.c
index 386314402..27a446de1 100644
--- a/src/flash/nor/stm32lx.c
+++ b/src/flash/nor/stm32lx.c
@@ -482,6 +482,11 @@ static int stm32lx_probe(struct flash_bank *bank)
 		flash_size_in_kb = 0xffff;
 	}
 
+	/* some variants read 0 for flash size register
+	 * use a max flash size as a default */
+	if (flash_size_in_kb == 0)
+		flash_size_in_kb = 0xffff;
+
 	if ((device_id & 0xfff) == 0x416) {
 		/* check for early silicon */
 		if (flash_size_in_kb == 0xffff) {