diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6ef94add5..dd6007197 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@
 
 - TCA9534: Added I2C GPIO expander driver (`src/dev/tca9534.h`) with shared-bus and owned-bus init, plus `TCA9534_GPIO` example.
 
+### Bug Fixes
+
+- CMake: `DATA_IN_D2_SRAM` is now defined, so `SystemInit()` enables the D2 AHB SRAM blocks that hold the DMA buffers. The Makefile build already did this.
+
 ## v8.1.0
 
 ### Features
diff --git a/Drivers/CMakeLists.txt b/Drivers/CMakeLists.txt
index 77fd3ce80..a52d4a6cf 100644
--- a/Drivers/CMakeLists.txt
+++ b/Drivers/CMakeLists.txt
@@ -12,6 +12,11 @@ target_include_directories(CMSIS_DEVICE_H7 PUBLIC
 target_sources(CMSIS_DEVICE_H7 PRIVATE
   ${MODULE_DIR}/sys/system_stm32h7xx.c
 )
+# Enables the D2 AHB SRAM blocks in SystemInit(). DMA_BUFFER_MEM_SECTION places
+# DMA buffers there (.sram1_bss / RAM_D2), and the blocks are off out of reset.
+target_compile_definitions(CMSIS_DEVICE_H7 PRIVATE
+  DATA_IN_D2_SRAM
+)
 target_link_libraries(CMSIS_DEVICE_H7 PUBLIC
   CMSIS_CORE
   STM32H7XX_HAL_DRIVER