diff --git a/Makefile b/Makefile
index 977973e..e2982bd 100644
--- a/Makefile
+++ b/Makefile
@@ -29,6 +29,11 @@ ifeq ($(FULL_WARNINGS), yes)
 	CFLAGS += -Wall -Wextra -Wpedantic -Wno-unused-parameter -Wno-unused-function -Wconversion -Wdouble-promotion -Wno-sign-conversion -fsanitize=undefined -fsanitize-trap
 endif
 
+DONT_SHADOW_SHIFTS = no
+ifeq ($(DONT_SHADOW_SHIFTS), yes)
+	CFLAGS += -DDONT_SHADOW_SHIFTS=1
+endif
+
 DOTOS = src/emu_serial.o \
 	src/emu_emulate.o \
 	src/emu_init.o \
diff --git a/src/ui_sdl.c b/src/ui_sdl.c
index 323e892..7cac7b3 100644
--- a/src/ui_sdl.c
+++ b/src/ui_sdl.c
@@ -708,17 +708,19 @@ static int SDLKeyToKey( SDLKey k )
         case SDLK_ESCAPE:
             return HPKEY_ON;
             break;
+#ifndef DONT_SHADOW_SHIFTS
         case SDLK_LSHIFT:
             return HPKEY_SHL;
             break;
         case SDLK_RSHIFT:
-            return HPKEY_SHL;
+            return HPKEY_SHR;
             break;
+#endif
         case SDLK_LCTRL:
             return HPKEY_SHR;
             break;
         case SDLK_RCTRL:
-            return HPKEY_SHR;
+            return HPKEY_SHL;
             break;
         case SDLK_LALT:
             return HPKEY_ALPHA;
diff --git a/src/ui_x11.c b/src/ui_x11.c
index d441f96..0fb4900 100644
--- a/src/ui_x11.c
+++ b/src/ui_x11.c
@@ -2700,12 +2700,16 @@ int decode_key( XEvent* xev, KeySym sym, char* buf, int buflen )
             key_event( HPKEY_ON, xev );
             wake = 1;
             break;
+#ifndef DONT_SHADOW_SHIFTS
         case XK_Shift_L:
+#endif
         case XK_Control_R:
             key_event( HPKEY_SHL, xev );
             wake = 1;
             break;
+#ifndef DONT_SHADOW_SHIFTS
         case XK_Shift_R:
+#endif
         case XK_Control_L:
             key_event( HPKEY_SHR, xev );
             wake = 1;