diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3db11ee84..4511c597e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+### Bug Fixes
+
+- SDMMC: fix an issue where status flags were optimized out, resulting in very long while loops
+
 ## v8.0.0
 
 ### Features
diff --git a/src/util/sd_diskio.c b/src/util/sd_diskio.c
index e8310bd20..ff62b2bb6 100644
--- a/src/util/sd_diskio.c
+++ b/src/util/sd_diskio.c
@@ -57,8 +57,8 @@
 /* Disk status */
 static volatile DSTATUS Stat = STA_NOINIT;
 //static volatile  UINT  WriteStatus = 0, ReadStatus = 0;
-static uint32_t WriteStatus = 0;
-static uint32_t ReadStatus  = 0;
+static volatile uint32_t WriteStatus = 0;
+static volatile uint32_t ReadStatus  = 0;
 /* Private function prototypes -----------------------------------------------*/
 static DSTATUS SD_CheckStatus(BYTE lun);
 DSTATUS        SD_initialize(BYTE);