diff --git a/CHANGELOG.md b/CHANGELOG.md
index 859cf1e6..d0a7bc13 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -130,6 +130,9 @@
 * Foot process(es) sometimes remaining, using 100% CPU, when closing
   multiple foot windows at the same time
   (https://codeberg.org/dnkl/foot/issues/542).
+* Regression where `<mod>+shift+tab` always produced `\E[Z` instead of
+  the correct `\E[27;<mod>;9~` sequence
+  (https://codeberg.org/dnkl/foot/issues/547).
 
 
 ### Security
diff --git a/input.c b/input.c
index 320b1679..96c41a15 100644
--- a/input.c
+++ b/input.c
@@ -852,8 +852,7 @@ keymap_data_for_sym(xkb_keysym_t sym, size_t *count)
 }
 
 static const struct key_data *
-keymap_lookup(struct seat *seat, struct terminal *term,
-              xkb_keysym_t sym, enum modifier mods)
+keymap_lookup(struct terminal *term, xkb_keysym_t sym, enum modifier mods)
 {
     size_t count;
     const struct key_data *info = keymap_data_for_sym(sym, &count);
@@ -885,6 +884,18 @@ keymap_lookup(struct seat *seat, struct terminal *term,
     return NULL;
 }
 
+UNITTEST
+{
+    struct terminal term = {
+        .num_lock_modifier = false,
+        .keypad_keys_mode = KEYPAD_NUMERICAL,
+        .cursor_keys_mode = CURSOR_KEYS_NORMAL,
+    };
+
+    const struct key_data *info = keymap_lookup(&term, XKB_KEY_ISO_Left_Tab, MOD_SHIFT | MOD_CTRL);
+    xassert(strcmp(info->seq, "\033[27;6;9~") == 0);
+}
+
 static void
 key_press_release(struct seat *seat, struct terminal *term, uint32_t serial,
                   uint32_t key, uint32_t state)
@@ -1036,7 +1047,7 @@ key_press_release(struct seat *seat, struct terminal *term, uint32_t serial,
         static const struct key_data esc = {.seq = "\033[27;1;27~"};
         keymap = &esc;
     } else
-        keymap = keymap_lookup(seat, term, sym, keymap_mods);
+        keymap = keymap_lookup(term, sym, keymap_mods);
 
     if (keymap != NULL) {
         term_to_slave(term, keymap->seq, strlen(keymap->seq));
diff --git a/keymap.h b/keymap.h
index f1b4a0ea..f98647c3 100644
--- a/keymap.h
+++ b/keymap.h
@@ -82,19 +82,17 @@ static const struct key_data key_tab[] = {
  * Shift+Tab produces ISO_Left_Tab
  *
  * However, all combos (except Shift+Tab) acts as if we pressed
- * mods+shift+tab. XKB “consumes” shift for us, hence MOD_SHIFT isn’t
- * present in any of the entries below. However, the entries still map
- * to sequences that indicate shift has been pressed.
+ * mods+shift+tab.
  */
 static const struct key_data key_iso_left_tab[] = {
-    {MOD_ALT,                       CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[27;4;9~"},
-    {MOD_CTRL,                      CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[27;6;9~"},
-    {MOD_ALT | MOD_CTRL,            CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[27;8;9~"},
-    {MOD_META,                      CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[27;10;9~"},
-    {MOD_META | MOD_ALT,            CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[27;12;9~"},
-    {MOD_META | MOD_CTRL,           CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[27;14;9~"},
-    {MOD_META | MOD_ALT | MOD_CTRL, CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[27;16;9~"},
-    {MOD_ANY,                       CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[Z"},
+    {MOD_SHIFT | MOD_ALT,                       CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[27;4;9~"},
+    {MOD_SHIFT | MOD_CTRL,                      CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[27;6;9~"},
+    {MOD_SHIFT | MOD_ALT | MOD_CTRL,            CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[27;8;9~"},
+    {MOD_SHIFT | MOD_META,                      CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[27;10;9~"},
+    {MOD_SHIFT | MOD_META | MOD_ALT,            CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[27;12;9~"},
+    {MOD_SHIFT | MOD_META | MOD_CTRL,           CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[27;14;9~"},
+    {MOD_SHIFT | MOD_META | MOD_ALT | MOD_CTRL, CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[27;16;9~"},
+    {MOD_ANY,                                   CURSOR_KEYS_DONTCARE, KEYPAD_DONTCARE, "\033[Z"},
 };
 
 static const struct key_data key_backspace[] = {
diff --git a/macros.h b/macros.h
index 52c24e0e..7cfe777e 100644
--- a/macros.h
+++ b/macros.h
@@ -1,5 +1,7 @@
 #pragma once
 
+#define PASTE(a, b) a##b
+#define XPASTE(a, b) PASTE(a, b)
 #define DO_PRAGMA(x) _Pragma(#x)
 #define VERCMP(x, y, cx, cy) ((cx > x) || ((cx == x) && (cy >= y)))
 
@@ -68,6 +70,7 @@
 
 #if GNUC_AT_LEAST(3, 0) || HAS_ATTRIBUTE(constructor)
     #define CONSTRUCTOR __attribute__((__constructor__))
+    #define HAVE_ATTR_CONSTRUCTOR 1
 #else
     #define CONSTRUCTOR
 #endif
@@ -175,6 +178,19 @@
     #define UNROLL_LOOP(n)
 #endif
 
+#ifdef __COUNTER__
+    // Supported by GCC 4.3+ and Clang
+    #define COUNTER_ __COUNTER__
+#else
+    #define COUNTER_ __LINE__
+#endif
+
+#if defined(_DEBUG) && defined(HAVE_ATTR_CONSTRUCTOR)
+    #define UNITTEST static void CONSTRUCTOR XPASTE(unittest_, COUNTER_)(void)
+#else
+    #define UNITTEST static void UNUSED XPASTE(unittest_, COUNTER_)(void)
+#endif
+
 #ifdef __clang__
     #define IGNORE_WARNING(wflag) \
         DO_PRAGMA(clang diagnostic push) \