diff --git a/src/getchar.c b/src/getchar.c
index 2fa68a7..e2474be 100644
--- a/src/getchar.c
+++ b/src/getchar.c
@@ -1743,11 +1743,9 @@
 		--allow_keys;
 	    }
 
-	    // Get two extra bytes for special keys
+	    // Get two extra bytes for special keys, handle modifiers.
 	    if (c == K_SPECIAL
-#if defined(FEAT_GUI) || defined(MSWIN)
-		    // GUI codes start with CSI; MS-Windows sends mouse scroll
-		    // events with CSI.
+#ifdef FEAT_GUI
 		    || c == CSI
 #endif
 	       )
@@ -2520,32 +2518,12 @@
 	    && State != MODE_CONFIRM
 	    && !at_ins_compl_key())
     {
-#if defined(FEAT_GUI) || defined(MSWIN)
-	if (tb_c1 == CSI
-# if !defined(MSWIN)
-		&& gui.in_use
-# endif
-		&& typebuf.tb_len >= 2
-		&& (typebuf.tb_buf[typebuf.tb_off + 1] == KS_MODIFIER
-# if defined(MSWIN)
-		    || (typebuf.tb_len >= 3
-#  ifdef FEAT_GUI
-		      && !gui.in_use
-#  endif
-		      && typebuf.tb_buf[typebuf.tb_off + 1] == KS_EXTRA
-		      && (typebuf.tb_buf[typebuf.tb_off + 2] == KE_MOUSEUP
-			|| typebuf.tb_buf[typebuf.tb_off + 2] == KE_MOUSEDOWN
-			|| typebuf.tb_buf[typebuf.tb_off + 2] == KE_MOUSELEFT
-			|| typebuf.tb_buf[typebuf.tb_off + 2] == KE_MOUSERIGHT)
-		       )
-# endif
-		   )
-	   )
+#ifdef FEAT_GUI
+	if (gui.in_use && tb_c1 == CSI && typebuf.tb_len >= 2
+		&& typebuf.tb_buf[typebuf.tb_off + 1] == KS_MODIFIER)
 	{
 	    // The GUI code sends CSI KS_MODIFIER {flags}, but mappings expect
 	    // K_SPECIAL KS_MODIFIER {flags}.
-	    // MS-Windows sends mouse scroll events CSI KS_EXTRA {what}, but
-	    // non-GUI mappings expect K_SPECIAL KS_EXTRA {what}.
 	    tb_c1 = K_SPECIAL;
 	}
 #endif