diff --git a/libraries/wutdevoptab/devoptab_fs_read.c b/libraries/wutdevoptab/devoptab_fs_read.c
index 1f66a657..405b456b 100644
--- a/libraries/wutdevoptab/devoptab_fs_read.c
+++ b/libraries/wutdevoptab/devoptab_fs_read.c
@@ -28,13 +28,13 @@ ssize_t __wut_fs_read(struct _reent *r, void *fd, char *ptr, size_t len) {
       uint8_t *tmp = (uint8_t *) ptr;
       size_t size = len - bytesRead;
 
-      if ((uintptr_t) ptr & 0x3F) {
+      if (size < 0x40) {
+         // read partial cache-line back-end
+         tmp = alignedBuffer;
+      } else if ((uintptr_t) ptr & 0x3F) {
          // read partial cache-line front-end
          tmp = alignedBuffer;
          size = MIN(size, 0x40 - ((uintptr_t) ptr & 0x3F));
-      } else if (size < 0x40) {
-         // read partial cache-line back-end
-         tmp = alignedBuffer;
       } else {
          // read whole cache lines
          size &= ~0x3F;
diff --git a/libraries/wutdevoptab/devoptab_fs_write.c b/libraries/wutdevoptab/devoptab_fs_write.c
index f2cc747e..8fcd5f78 100644
--- a/libraries/wutdevoptab/devoptab_fs_write.c
+++ b/libraries/wutdevoptab/devoptab_fs_write.c
@@ -32,13 +32,13 @@ ssize_t __wut_fs_write(struct _reent *r, void *fd, const char *ptr, size_t len)
       uint8_t *tmp = (uint8_t *) ptr;
       size_t size = len - bytesWritten;
 
-      if ((uintptr_t) ptr & 0x3F) {
+      if (size < 0x40) {
+         // write partial cache-line back-end
+         tmp = alignedBuffer;
+      } else if ((uintptr_t) ptr & 0x3F) {
          // write partial cache-line front-end
          tmp = alignedBuffer;
          size = MIN(size, 0x40 - ((uintptr_t) ptr & 0x3F));
-      } else if (size < 0x40) {
-         // write partial cache-line back-end
-         tmp = alignedBuffer;
       } else {
          // write whole cache lines
          size &= ~0x3F;