diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index bd1cfe6..a788232 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -30,7 +30,7 @@ jobs:
           sudo apt update
           sudo apt install -y \
             doxygen libxcb-xkb-dev valgrind ninja-build \
-            libwayland-dev wayland-protocols bison graphviz
+            libwayland-dev wayland-protocols bison graphviz libicu-dev
       - name: Install xkeyboard-config
         run: |
           # Install master version of xkeyboard-config, in order to ensure
diff --git a/meson.build b/meson.build
index 97561fe..5f31f6a 100644
--- a/meson.build
+++ b/meson.build
@@ -651,10 +651,18 @@ if get_option('enable-x11')
         ],
     )
 endif
+# TODO: version range?
+keysyms_test_dep = [test_dep]
+keysyms_test_c_args = ['-DENABLE_PRIVATE_APIS']
+icu_dep = dependency('icu-uc', required: false)
+if icu_dep.found()
+    keysyms_test_dep += [icu_dep]
+    configh_data.set10('HAVE_ICU', true)
+endif
 test(
     'keysym',
-    executable('test-keysym', 'test/keysym.c', dependencies: test_dep,
-               c_args: ['-DENABLE_PRIVATE_APIS']),
+    executable('test-keysym', 'test/keysym.c', dependencies: keysyms_test_dep,
+               c_args: keysyms_test_c_args),
     env: test_env,
 )
 test(
diff --git a/test/keysym.c b/test/keysym.c
index dacd8d8..891c754 100644
--- a/test/keysym.c
+++ b/test/keysym.c
@@ -24,6 +24,9 @@
 
 #include <locale.h>
 #include <stdbool.h>
+#if HAVE_ICU
+#include <unicode/uchar.h>
+#endif
 
 #include "test.h"
 #include "keysym.h" /* For unexported is_lower/upper/keypad() */
@@ -169,6 +172,87 @@ test_utf8(xkb_keysym_t keysym, const char *expected)
     return streq(s, expected);
 }
 
+#if HAVE_ICU
+
+static inline uint32_t
+to_simple_lower(uint32_t cp)
+{
+    return (uint32_t)u_tolower((UChar32) cp);
+}
+
+static inline uint32_t
+to_simple_upper(uint32_t cp)
+{
+    return (uint32_t)u_toupper((UChar32) cp);
+}
+
+#define KEYSYM     "0x%04"PRIx32
+#define CODE_POINT "U+%04"PRIX32
+
+static void
+test_icu_case_mappings(xkb_keysym_t ks)
+{
+    /* Check lower case mapping */
+    xkb_keysym_t ks_mapped = xkb_keysym_to_lower(ks);
+    uint32_t cp = xkb_keysym_to_utf32(ks);
+    uint32_t expected = to_simple_lower(cp);
+    if (ks_mapped && ks_mapped != ks) {
+        uint32_t got = xkb_keysym_to_utf32(ks_mapped);
+        assert_printf(got == expected,
+                      "Invalid xkb_keysym_to_lower("KEYSYM") == "KEYSYM": "
+                      "expected "CODE_POINT", got: "CODE_POINT"\n",
+                      ks, ks_mapped, expected, got);
+        got = !!xkb_keysym_is_upper(ks);
+        expected = !!(u_isUUppercase(cp) || u_istitle(cp));
+        assert_printf(got == expected || u_istitle(cp),
+                      "Invalid xkb_keysym_is_upper("KEYSYM") ("CODE_POINT"): "
+                      "expected %d, got: %d\n",
+                      ks, cp, expected, got);
+        if (u_istitle(cp)) {
+            fprintf(stderr,
+                    "%s title case handling "KEYSYM" ("CODE_POINT")\n",
+                    (got == expected) ? "[INFO] valid" : "[WARNING] invalid",
+                    ks, cp);
+        }
+    } else if (expected != cp) {
+        fprintf(stderr,
+                "[WARNING] missing lower case mapping for "KEYSYM": "
+                "expected "CODE_POINT", got: "CODE_POINT"\n",
+                ks, expected, cp);
+        assert_printf(!xkb_keysym_is_upper(ks),
+                      "Invalid xkb_keysym_is_upper("KEYSYM") ("CODE_POINT"): "
+                      "expected false, got: true\n",
+                      ks, cp);
+    }
+
+    /* Check upper case mapping */
+    ks_mapped = xkb_keysym_to_upper(ks);
+    expected = to_simple_upper(cp);
+    if (ks_mapped && ks_mapped != ks) {
+        uint32_t got = xkb_keysym_to_utf32(ks_mapped);
+        assert_printf(got == expected,
+                      "Invalid xkb_keysym_to_upper("KEYSYM") == "KEYSYM": "
+                      "expected "CODE_POINT", got: "CODE_POINT"\n",
+                      ks, ks_mapped, expected, got);
+        got = !!xkb_keysym_is_lower(ks);
+        expected = !!u_isULowercase(cp);
+        assert_printf(got == expected,
+                      "Invalid xkb_keysym_is_lower("KEYSYM") ("CODE_POINT"): "
+                      "expected %d, got: %d\n",
+                      ks, cp, expected, got);
+    } else if (expected != cp) {
+        fprintf(stderr,
+                "[WARNING] missing upper case mapping for "KEYSYM": "
+                "expected "CODE_POINT", got: "CODE_POINT"\n",
+                ks, expected, cp);
+        assert_printf(!xkb_keysym_is_lower(ks),
+                      "Invalid xkb_keysym_is_lower("KEYSYM") ("CODE_POINT"): "
+                      "expected false, got: true\n",
+                      ks, cp);
+    }
+}
+#endif
+
 static void
 test_github_issue_42(void)
 {
@@ -285,6 +369,10 @@ main(void)
                       "xkb_keysym_is_keypad(0x%04"PRIx32") \"%s\": "
                       "expected %d, got: %d\n",
                       ks, name, expected, got);
+#if HAVE_ICU
+        /* Check case mappings */
+        test_icu_case_mappings(ks);
+#endif
     }
     iter = xkb_keysym_iterator_unref(iter);
     assert(ks_prev == XKB_KEYSYM_MAX_ASSIGNED);