diff --git a/meson.build b/meson.build
index d55ae08..97561fe 100644
--- a/meson.build
+++ b/meson.build
@@ -623,6 +623,7 @@ libxkbcommon_test_internal = static_library(
     'bench/bench.h',
     libxkbcommon_sources,
     include_directories: include_directories('src', 'include'),
+    c_args: ['-DENABLE_PRIVATE_APIS'],
 )
 test_dep = declare_dependency(
     include_directories: include_directories('src', 'include'),
@@ -652,7 +653,8 @@ if get_option('enable-x11')
 endif
 test(
     'keysym',
-    executable('test-keysym', 'test/keysym.c', dependencies: test_dep),
+    executable('test-keysym', 'test/keysym.c', dependencies: test_dep,
+               c_args: ['-DENABLE_PRIVATE_APIS']),
     env: test_env,
 )
 test(
diff --git a/src/keysym.c b/src/keysym.c
index 192ba20..cd2565c 100644
--- a/src/keysym.c
+++ b/src/keysym.c
@@ -55,6 +55,36 @@
 #include "keysym.h"
 #include "ks_tables.h"
 
+static ssize_t
+find_keysym_index(xkb_keysym_t ks)
+{
+    /* Lower bound:
+     * keysym_to_name[0].keysym
+     * == XKB_KEYSYM_MIN_EXPLICIT == XKB_KEYSYM_MIN == 0
+     * No need to check: xkb_keysym_t is unsigned.
+     *
+     * Upper bound:
+     * keysym_to_name[ARRAY_SIZE(keysym_to_name) - 1].keysym
+     * == XKB_KEYSYM_MAX_EXPLICIT <= XKB_KEYSYM_MAX
+     */
+    if (ks > XKB_KEYSYM_MAX_EXPLICIT)
+        return -1;
+
+    ssize_t lo = 0, hi = ARRAY_SIZE(keysym_to_name) - 1;
+    while (hi >= lo) {
+        ssize_t mid = (lo + hi) / 2;
+        if (ks > keysym_to_name[mid].keysym) {
+            lo = mid + 1;
+        } else if (ks < keysym_to_name[mid].keysym) {
+            hi = mid - 1;
+        } else {
+            return mid;
+        }
+    }
+
+    return -1;
+}
+
 static inline const char *
 get_name(const struct name_keysym *entry)
 {
@@ -69,17 +99,9 @@ xkb_keysym_get_name(xkb_keysym_t ks, char *buffer, size_t size)
         return -1;
     }
 
-    int32_t lo = 0, hi = ARRAY_SIZE(keysym_to_name) - 1;
-    while (hi >= lo) {
-        int32_t mid = (lo + hi) / 2;
-        if (ks > keysym_to_name[mid].keysym) {
-            lo = mid + 1;
-        } else if (ks < keysym_to_name[mid].keysym) {
-            hi = mid - 1;
-        } else {
-            return snprintf(buffer, size, "%s", get_name(&keysym_to_name[mid]));
-        }
-    }
+    ssize_t index = find_keysym_index(ks);
+    if (index != -1)
+        return snprintf(buffer, size, "%s", get_name(&keysym_to_name[index]));
 
     /* Unnamed Unicode codepoint. */
     if (ks >= XKB_KEYSYM_UNICODE_MIN && ks <= XKB_KEYSYM_UNICODE_MAX) {
@@ -91,6 +113,13 @@ xkb_keysym_get_name(xkb_keysym_t ks, char *buffer, size_t size)
     return snprintf(buffer, size, "0x%08x", ks);
 }
 
+bool
+xkb_keysym_is_assigned(xkb_keysym_t ks)
+{
+    return (XKB_KEYSYM_UNICODE_MIN <= ks && ks <= XKB_KEYSYM_UNICODE_MAX) ||
+           find_keysym_index(ks) != -1;
+}
+
 /*
  * Parse the numeric part of a 0xXXXX and UXXXX keysym.
  * Not using strtoul -- it's slower and accepts a bunch of stuff
diff --git a/src/keysym.h b/src/keysym.h
index 03a2c3e..916ae71 100644
--- a/src/keysym.h
+++ b/src/keysym.h
@@ -50,6 +50,9 @@
 #ifndef KEYSYM_H
 #define KEYSYM_H
 
+#include <stdbool.h>
+#include "xkbcommon/xkbcommon.h"
+
 /*
  * NOTE: this is not defined in xkbcommon.h, because if we did, it may add
  * overhead for library user: when handling keysyms they would also need to
@@ -74,6 +77,9 @@
 /** Maximum Unicode keysym, correspoding to the maximum Unicode code point */
 #define XKB_KEYSYM_UNICODE_MAX    0x0110ffff
 
+bool
+xkb_keysym_is_assigned(xkb_keysym_t ks);
+
 bool
 xkb_keysym_is_lower(xkb_keysym_t keysym);
 
diff --git a/src/keysym.h.jinja b/src/keysym.h.jinja
index 762eeb4..096a61c 100644
--- a/src/keysym.h.jinja
+++ b/src/keysym.h.jinja
@@ -50,6 +50,9 @@
 #ifndef KEYSYM_H
 #define KEYSYM_H
 
+#include <stdbool.h>
+#include "xkbcommon/xkbcommon.h"
+
 /*
  * NOTE: this is not defined in xkbcommon.h, because if we did, it may add
  * overhead for library user: when handling keysyms they would also need to
@@ -74,6 +77,9 @@
 /** Maximum Unicode keysym, correspoding to the maximum Unicode code point */
 #define XKB_KEYSYM_UNICODE_MAX    0x0110ffff
 
+bool
+xkb_keysym_is_assigned(xkb_keysym_t ks);
+
 bool
 xkb_keysym_is_lower(xkb_keysym_t keysym);
 
diff --git a/test/keysym.c b/test/keysym.c
index a2b1fce..17488c1 100644
--- a/test/keysym.c
+++ b/test/keysym.c
@@ -147,6 +147,32 @@ main(void)
     assert(XKB_KEYSYM_UNICODE_MIN < XKB_KEYSYM_UNICODE_MAX);
     assert(XKB_KEYSYM_UNICODE_MAX <= XKB_KEYSYM_MAX_EXPLICIT);
 
+    /* Assigned keysyms */
+    assert(xkb_keysym_is_assigned(XKB_KEYSYM_MIN));
+    assert(xkb_keysym_is_assigned(XKB_KEYSYM_MIN_ASSIGNED));
+    assert(xkb_keysym_is_assigned(XKB_KEY_space));
+    assert(xkb_keysym_is_assigned(XKB_KEY_nobreakspace));
+    assert(xkb_keysym_is_assigned(XKB_KEY_Aogonek));
+    assert(xkb_keysym_is_assigned(XKB_KEY_Hstroke));
+    assert(xkb_keysym_is_assigned(XKB_KEY_kra));
+    assert(xkb_keysym_is_assigned(XKB_KEY_braille_dot_1));
+    assert(xkb_keysym_is_assigned(XKB_KEY_XF86KbdLcdMenu5));
+    assert(xkb_keysym_is_assigned(XKB_KEY_Shift_L));
+    assert(xkb_keysym_is_assigned(XKB_KEY_XF86MonBrightnessUp));
+    assert(xkb_keysym_is_assigned(XKB_KEY_VoidSymbol));
+    assert(xkb_keysym_is_assigned(XKB_KEYSYM_UNICODE_MIN));
+    assert(xkb_keysym_is_assigned((XKB_KEYSYM_UNICODE_MIN + XKB_KEYSYM_UNICODE_MAX) / 2));
+    assert(xkb_keysym_is_assigned(XKB_KEYSYM_UNICODE_MAX));
+    assert(xkb_keysym_is_assigned(XKB_KEYSYM_MAX_ASSIGNED));
+    assert(!xkb_keysym_is_assigned(XKB_KEYSYM_MAX));
+
+    for (xkb_keysym_t ks = XKB_KEYSYM_MIN; ks <= XKB_KEYSYM_MAX; ks++) {
+        if (!xkb_keysym_is_assigned(ks))
+            continue;
+        /* Check assigned keysyms bounds */
+        assert(XKB_KEYSYM_MIN_ASSIGNED <= (int32_t)ks && ks <= XKB_KEYSYM_MAX_ASSIGNED);
+    }
+
     /* Named keysyms */
     assert(test_string("NoSymbol", XKB_KEY_NoSymbol));
     assert(test_string("Undo", 0xFF65));