diff --git a/src/lcd.cpp b/src/lcd.cpp
index a05d8cb32..9049723bc 100644
--- a/src/lcd.cpp
+++ b/src/lcd.cpp
@@ -33,7 +33,7 @@
 
 #include "open9x.h"
 
-uint8_t displayBuf[DISPLAY_W*(DISPLAY_H+7)/8];
+uint8_t displayBuf[DISPLAY_BUF_SIZE];
 #define DISPLAY_END (displayBuf+sizeof(displayBuf))
 #define ASSERT_IN_DISPLAY(p) assert((p) >= displayBuf && (p) < DISPLAY_END)
 
diff --git a/src/lcd.h b/src/lcd.h
index 98c676496..89c720467 100644
--- a/src/lcd.h
+++ b/src/lcd.h
@@ -115,7 +115,8 @@
 #define LcdFlags uint8_t
 #endif
 
-extern uint8_t displayBuf[DISPLAY_W*(DISPLAY_H+7)/8];
+#define DISPLAY_BUF_SIZE (DISPLAY_W*((DISPLAY_H+7)/8))
+extern uint8_t displayBuf[DISPLAY_BUF_SIZE];
 extern uint8_t lcdLastPos;
 
 #if defined(PCBSTD) && defined(VOICE)