diff --git a/ports/stm32f4/boards/STM32F401.ld b/ports/stm32f4/boards/STM32F401.ld
index b3d772a784..be72ecc091 100644
--- a/ports/stm32f4/boards/STM32F401.ld
+++ b/ports/stm32f4/boards/STM32F401.ld
@@ -1,28 +1,52 @@
 /*
-    GNU linker script for STM32F401 with bootloader (such as the Meowbit)
+    GNU linker script for STM32F401 with bootloader (from Meowbit Micropython)
+    Doesn't work: 
+
+    Traceback (most recent call last):
+  File "../../tools/build_memory_info.py", line 64, in <module>
+    regions[region] = int(eval(space))
+  File "<string>", line 1, in <module>
+NameError: name 'FLASH_ISR' is not defined
 */
 
 /* Specify the memory areas */
+/*     FLASH_FS (rx)   : ORIGIN = 0x08020000, LENGTH = 128K */
+/* sectors 5 128K */
 MEMORY
 {
-    FLASH (rx)      : ORIGIN = 0x08000000, LENGTH = 512K - 64K /* entire flash, sans bootloader */
-    FLASH_ISR (rx)  : ORIGIN = 0x08000000, LENGTH = 64K /* sector 4, 0-3 used by bootloader*/
-    FLASH_TEXT (rx) : ORIGIN = 0x08010000, LENGTH = 384K /* sector 4 is 64K, sectors 5,6,7 are 128K */
-    RAM (xrw)       : ORIGIN = 0x20000194, LENGTH = 96K - 0x194 /* more bootloader schnenaigans */
+    FLASH (rx)      : ORIGIN = 0x08010000, LENGTH = 512K - 64K /* entire flash */
+    FLASH_ISR (rx)  : ORIGIN = 0x08010000, LENGTH = 64K /* sector 4, sec 0~3 reserved for booloader */
+    FLASH_TEXT (rx) : ORIGIN = 0x08020000, LENGTH = 384K /* sectors 5, 6,7 are 128K */
+    RAM (xrw)       : ORIGIN = 0x20000194, LENGTH = 96K - 0x194
 }
 
 /* produce a link error if there is not this amount of RAM for these sections */
 _minimum_stack_size = 2K;
 _minimum_heap_size = 16K;
 
-/* Define tho top end of the stack.  The stack is full descending so begins just
-   above last byte of RAM.  Note that EABI requires the stack to be 8-byte
-   aligned for a call. */
-_estack = ORIGIN(RAM) + LENGTH(RAM);
+/* Define the stack.  The stack is full descending so begins just above last byte
+   of RAM.  Note that EABI requires the stack to be 8-byte aligned for a call. */
+_estack = ORIGIN(RAM) + LENGTH(RAM) - _estack_reserve;
+_sstack = _estack - 16K; /* tunable */
 
 /* RAM extents for the garbage collector */
 _ram_start = ORIGIN(RAM);
 _ram_end = ORIGIN(RAM) + LENGTH(RAM);
+_heap_start = _ebss; /* heap starts just after statically allocated memory */
+_heap_end = _sstack;
+
+/* Memory layout for internal flash storage configuration:
+
+    FLASH_ISR   .isr_vector
+
+    FLASH_TEXT  .text
+    FLASH_TEXT  .data
+
+    RAM         .data
+    RAM         .bss
+    RAM         .heap
+    RAM         .stack
+*/
 
 ENTRY(Reset_Handler)
 
@@ -36,8 +60,25 @@ SECTIONS
         KEEP(*(.isr_vector)) /* Startup code */
 
         /* This first flash block is 16K annd the isr vectors only take up
-           about 400 bytes. Micropython pads this with files, but this didn't
-           work with the size of Circuitpython's ff object. */
+           about 400 bytes. So we pull in a couple of object files to pad it
+           out. */
+
+        . = ALIGN(4);
+
+        /* NOTE: If you update the list of files contained in .isr_vector,
+                 then be sure to also update smhal/Makefile where it forcibly
+           builds each of these files with -Os */
+
+        */ff.o(.text*)
+        */vfs_fat_*.o(.text*)
+        */py/formatfloat.o(.text*)
+        */py/parsenum.o(.text*)
+        */py/mpprint.o(.text*)
+
+        */py/compile.o(.text*)
+        */py/objset.o(.text*)
+        */py/mpz.o(.text*)
+        */py/vm.o(.text*)
 
         . = ALIGN(4);
     } >FLASH_ISR
@@ -102,5 +143,3 @@ SECTIONS
 
     .ARM.attributes 0 : { *(.ARM.attributes) }
 }
-
-
diff --git a/ports/stm32f4/boards/STM32F401_boot.ld b/ports/stm32f4/boards/STM32F401_boot.ld
index 7f582fdf9f..64f78451ad 100644
--- a/ports/stm32f4/boards/STM32F401_boot.ld
+++ b/ports/stm32f4/boards/STM32F401_boot.ld
@@ -5,10 +5,10 @@
 /* Specify the memory areas */
 MEMORY
 {
-    FLASH (rx)      : ORIGIN = 0x08010000, LENGTH = 512K - 64K /* entire flash, sans bootloader */
-    FLASH_ISR (rx)  : ORIGIN = 0x08010000, LENGTH = 64K /* sector 4, 0-3 used by bootloader*/
+    FLASH (rx)      : ORIGIN = 0x08010000, LENGTH = 512K - 64K /* entire flash */
+    FLASH_ISR (rx)  : ORIGIN = 0x08010000, LENGTH = 64K 
     FLASH_TEXT (rx) : ORIGIN = 0x08020000, LENGTH = 384K /* sector 4 is 64K, sectors 5,6,7 are 128K */
-    RAM (xrw)       : ORIGIN = 0x20000194, LENGTH = 96K - 0x194 /* more bootloader schnenaigans */
+    RAM (xrw)       : ORIGIN = 0x20000000, LENGTH = 96K
 }
 
 /* produce a link error if there is not this amount of RAM for these sections */