diff --git a/Makefile b/Makefile
index d46e413..67fef7f 100644
--- a/Makefile
+++ b/Makefile
@@ -20,6 +20,10 @@ ifeq (${LANG},DE)
 	SHARED_FLAGS += -DLANG_DE
 endif
 
+ifeq (${INVERTED},1)
+        SHARED_FLAGS += -DINVERTED
+endif
+
 CFLAGS += ${SHARED_FLAGS} -std=c11
 CXXFLAGS += ${SHARED_FLAGS} -std=c++11 -fno-rtti -fno-exceptions
 
diff --git a/README.md b/README.md
index 857a518..44b51a9 100644
--- a/README.md
+++ b/README.md
@@ -75,3 +75,9 @@ presence anymore"). This is quite improbable, though.
 
 Please remove and insert the battery again. Make sure that the battery has enough
 current and replcace the battery if the LED are dark.
+
+## Wrong display ordered
+
+If you ordered the wrong display (AS instead BS variant, e.g. for Mini Rocket 
+788AS (Common Cathode) instead 788BS (Common Anode), you can set the build 
+parameter `INVERTED=1` to build a corresponding firmware.
diff --git a/src/display.cc b/src/display.cc
index 01b744a..dc34698 100644
--- a/src/display.cc
+++ b/src/display.cc
@@ -31,7 +31,13 @@ Display::Display()
 void Display::disable()
 {
 	TIMSK0 &= ~_BV(TOIE0);
+	
+	#ifdef INVERTED
+	PORTB = 0xFF;
+	#else
 	PORTB = 0;
+	#endif
+	
 	PORTD = 0;
 }
 
@@ -53,9 +59,19 @@ void Display::multiplex()
 	 * To avoid flickering, do not put any code (or expensive index
 	 * calculations) between the following three lines.
 	 */
+	#ifdef INVERTED
+	PORTB = 0xFF;
+	#else
 	PORTB = 0;
+	#endif
+	
 	PORTD = disp_buf[active_col];
+	
+	#ifdef INVERTED
+	PORTB = ~_BV(active_col);
+	#else
 	PORTB = _BV(active_col);
+	#endif
 
 	if (++active_col == 8) {
 		active_col = 0;
@@ -109,21 +125,41 @@ void Display::update() {
 				 */
 				if (current_anim->direction == 0) {
 					if (char_pos == 0) {
+						#ifdef INVERTED
+						disp_buf[7] = 0x00; // whitespace
+						#else
 						disp_buf[7] = 0xff; // whitespace
+						#endif
 					} else {
+						#ifdef INVERTED
+						disp_buf[7] = pgm_read_byte(&glyph_addr[char_pos]);
+						#else
 						disp_buf[7] = ~pgm_read_byte(&glyph_addr[char_pos]);
+						#endif
 					}
 				} else {
 					if (char_pos == 0) {
+						#ifdef INVERTED
+						disp_buf[0] = 0x00; // whitespace
+						#else
 						disp_buf[0] = 0xff; // whitespace
+						#endif
 					} else {
+						#ifdef INVERTED
+						disp_buf[0] = pgm_read_byte(&glyph_addr[glyph_len - char_pos + 1]);
+						#else
 						disp_buf[0] = ~pgm_read_byte(&glyph_addr[glyph_len - char_pos + 1]);
+						#endif
 					}
 				}
 
 			} else if (current_anim->type == AnimationType::FRAMES) {
 				for (i = 0; i < 8; i++) {
+					#ifdef INVERTED
+					disp_buf[i] = current_anim->data[str_pos+i];
+					#else
 					disp_buf[i] = ~current_anim->data[str_pos+i];
+					#endif
 				}
 				str_pos += 8;
 			}
@@ -222,8 +258,15 @@ void Display::update() {
 
 void Display::reset()
 {
-	for (uint8_t i = 0; i < 8; i++)
+	for (uint8_t i = 0; i < 8; i++) {
+		#ifdef INVERTED
+		disp_buf[i] = 0x00;
+		#else
 		disp_buf[i] = 0xff;
+		#endif
+	}
+	
+		
 	update_cnt = 0;
 	repeat_cnt = 0;
 	str_pos = 0;
diff --git a/src/system.h b/src/system.h
index 9229e1b..582d290 100644
--- a/src/system.h
+++ b/src/system.h
@@ -12,7 +12,7 @@
 
 // to display firmware version (v2.1) when storage is empty on first turn on
 #define FW_REV_MAJOR  2
-#define FW_REV_MINOR  1
+#define FW_REV_MINOR  2