diff --git a/include/arch/arm/cortex_m/scripts/linker.ld b/include/arch/arm/cortex_m/scripts/linker.ld
index 6c3d23717c9..1f8b1cc5a59 100644
--- a/include/arch/arm/cortex_m/scripts/linker.ld
+++ b/include/arch/arm/cortex_m/scripts/linker.ld
@@ -518,4 +518,13 @@ SECTIONS
 	KEEP(*(.gnu.attributes))
 	}
 
+/* Must be last in romable region */
+SECTION_PROLOGUE(.last_section,(NOLOAD),)
+{
+} GROUP_LINK_IN(ROMABLE_REGION)
+
+/* To provide the image size as a const expression,
+ * calculate this value here. */
+_flash_used = LOADADDR(.last_section) - _image_rom_start;
+
     }
diff --git a/include/linker/linker-defs.h b/include/linker/linker-defs.h
index f7a96898bdf..bb95f421235 100644
--- a/include/linker/linker-defs.h
+++ b/include/linker/linker-defs.h
@@ -233,6 +233,9 @@ extern char _image_rom_start[];
 extern char _image_rom_end[];
 extern char _image_rom_size[];
 
+/* Includes all ROMable data, i.e. the size of the output image file. */
+extern char _flash_used[];
+
 /* datas, bss, noinit */
 extern char _image_ram_start[];
 extern char _image_ram_end[];