diff --git a/client/CMakeLists.txt b/client/CMakeLists.txt
index 90885359..7cb29834 100644
--- a/client/CMakeLists.txt
+++ b/client/CMakeLists.txt
@@ -152,6 +152,8 @@ set(SOURCES
 
 # Force cimgui to build as a static library.
 set(IMGUI_STATIC "yes" CACHE STRING "Build as a static library")
+# Support Unicode codepoints outside the basic multilingual plane.
+set(IMGUI_WCHAR32 "yes")
 add_definitions("-DCIMGUI_USE_OPENGL2=1")
 add_definitions("-DCIMGUI_USE_OPENGL3=1")
 
diff --git a/client/include/app.h b/client/include/app.h
index 5c73d9b0..6360c980 100644
--- a/client/include/app.h
+++ b/client/include/app.h
@@ -131,6 +131,11 @@ void app_freeOverlays(void);
  */
 void app_invalidateOverlay(bool renderTwice);
 
+/**
+ * Ensure that user-supplied UTF-8 text has glyphs in the UI font atlas.
+ */
+void app_registerImGuiText(const char * text);
+
 struct OverlayGraph;
 typedef struct OverlayGraph * GraphHandle;
 typedef const char * (*GraphFormatFn)(const char * name,
diff --git a/client/include/util.h b/client/include/util.h
index 1382f4ae..111dd56c 100644
--- a/client/include/util.h
+++ b/client/include/util.h
@@ -26,6 +26,9 @@
 #include "common/types.h"
 #include "common/util.h"
 
+struct ImFont;
+struct ImFontAtlas;
+
 // reads the specified file into a new buffer
 // the callee must free the buffer
 bool util_fileGetContents(const char * filename, char ** buffer, size_t * length);
@@ -46,5 +49,8 @@ static inline double util_clamp(double x, double min, double max)
 bool util_initUIFonts(void);
 void util_freeUIFonts(void);
 char * util_getUIFont(const char * fontName);
+bool util_uiFontAddText(const char * text);
+bool util_buildUIFontAtlas(
+    struct ImFontAtlas * atlas, float size, struct ImFont ** large);
 
 #endif
diff --git a/client/renderers/EGL/filter_glsl.c b/client/renderers/EGL/filter_glsl.c
index cbc9577f..b7605a8e 100644
--- a/client/renderers/EGL/filter_glsl.c
+++ b/client/renderers/EGL/filter_glsl.c
@@ -1080,6 +1080,7 @@ static bool createFilter(const char * root, const char * relative,
   char * extension = strrchr((char *)this->base.ops.name, '.');
   if (extension && !strcasecmp(extension, ".glsl"))
     *extension = '\0';
+  app_registerImGuiText(this->base.ops.name);
 
   parseFile(this);
   this->enable = enabledInOption(this->base.ops.id);
diff --git a/client/renderers/EGL/postprocess.c b/client/renderers/EGL/postprocess.c
index 15119bfe..3951f37c 100644
--- a/client/renderers/EGL/postprocess.c
+++ b/client/renderers/EGL/postprocess.c
@@ -159,6 +159,7 @@ static void loadPresetList(struct EGL_PostProcess * this)
       goto fail;
     }
     stringlist_push(this->presets, name);
+    app_registerImGuiText(name);
 
     if (preset && strcmp(preset, name) == 0)
       this->activePreset = stringlist_count(this->presets) - 1;
diff --git a/client/src/app.c b/client/src/app.c
index 3c8881ba..ed6c79ce 100644
--- a/client/src/app.c
+++ b/client/src/app.c
@@ -569,6 +569,7 @@ void app_handleKeyRelease(int sc)
 
 void app_handleKeyboardTyped(const char * typed)
 {
+  app_registerImGuiText(typed);
   ImGuiIO_AddInputCharactersUTF8(g_state.io, typed);
 }
 
@@ -1151,6 +1152,15 @@ void app_overlayConfigRegisterTab(const char * title,
   overlayConfig_registerTab(title, callback, udata);
 }
 
+void app_registerImGuiText(const char * text)
+{
+  if (!util_uiFontAddText(text))
+    return;
+
+  atomic_fetch_add(&g_state.lgrResize, 1);
+  app_invalidateOverlay(false);
+}
+
 void app_invalidateOverlay(bool renderTwice)
 {
   if (app_getState() == APP_STATE_SHUTDOWN)
diff --git a/client/src/main.c b/client/src/main.c
index 8ee78e58..a374cf7f 100644
--- a/client/src/main.c
+++ b/client/src/main.c
@@ -269,12 +269,8 @@ static int renderThread(void * unused)
       };
       g_state.io->FontGlobalScale = 1.0f / g_state.windowScale;
 
-      ImFontAtlas_Clear(g_state.io->Fonts);
-      ImFontAtlas_AddFontFromFileTTF(g_state.io->Fonts, g_state.fontName,
-        g_params.uiSize * g_state.windowScale, NULL, g_state.fontRange.Data);
-      g_state.fontLarge = ImFontAtlas_AddFontFromFileTTF(g_state.io->Fonts,
-        g_state.fontName, 1.3f * g_params.uiSize * g_state.windowScale, NULL, g_state.fontRange.Data);
-      if (!ImFontAtlas_Build(g_state.io->Fonts))
+      if (!util_buildUIFontAtlas(g_state.io->Fonts,
+            g_params.uiSize * g_state.windowScale, &g_state.fontLarge))
         DEBUG_FATAL("Failed to build font atlas: %s (%s)", g_params.uiFont, g_state.fontName);
 
       if (g_state.lgr)
@@ -1103,22 +1099,19 @@ static int lg_run(void)
   g_state.io->BackendFlags |= ImGuiBackendFlags_HasMouseCursors;
 
   g_state.windowScale = 1.0;
-  if (util_initUIFonts())
+  if (!util_initUIFonts())
   {
-    g_state.fontName = util_getUIFont(g_params.uiFont);
-    DEBUG_INFO("Using font: %s", g_state.fontName);
+    DEBUG_ERROR("Failed to initialize UI fonts");
+    return -1;
   }
 
-  ImVector_ImWchar_Init(&g_state.fontRange);
-  ImFontGlyphRangesBuilder * rangeBuilder =
-    ImFontGlyphRangesBuilder_ImFontGlyphRangesBuilder();
-  ImFontGlyphRangesBuilder_AddRanges(rangeBuilder, (ImWchar[]) {
-    0x0020, 0x00FF, // Basic Latin + Latin Supplement
-    0x2190, 0x2193, // four directional arrows
-    0,
-  });
-  ImFontGlyphRangesBuilder_BuildRanges(rangeBuilder, &g_state.fontRange);
-  ImFontGlyphRangesBuilder_destroy(rangeBuilder);
+  g_state.fontName = util_getUIFont(g_params.uiFont);
+  if (!g_state.fontName)
+  {
+    DEBUG_ERROR("Failed to load UI font: %s", g_params.uiFont);
+    return -1;
+  }
+  DEBUG_INFO("Using font: %s", g_state.fontName);
 
   // initialize metrics ringbuffers
   g_state.renderTimings  = ringbuffer_new(256, sizeof(float));
@@ -1612,7 +1605,6 @@ static void lg_shutdown(void)
   ringbuffer_free(&g_state.renderDuration);
 
   free(g_state.fontName);
-  ImVector_ImWchar_UnInit(&g_state.fontRange);
   igDestroyContext(NULL);
   free(g_state.imGuiIni);
 }
diff --git a/client/src/main.h b/client/src/main.h
index b430d4b1..a9a4d05f 100644
--- a/client/src/main.h
+++ b/client/src/main.h
@@ -64,7 +64,6 @@ struct AppState
   struct ll      * overlays;
   char           * fontName;
   ImFont         * fontLarge;
-  ImVector_ImWchar fontRange;
   bool             overlayInput;
   ImGuiMouseCursor cursorLast;
   char           * imGuiIni;
diff --git a/client/src/util.c b/client/src/util.c
index 36ac3e85..ac722fcd 100644
--- a/client/src/util.c
+++ b/client/src/util.c
@@ -30,7 +30,228 @@
 #include <math.h>
 #include <fontconfig/fontconfig.h>
 
+struct UIFontFace
+{
+  char * file;
+  int index;
+  ImVector_ImWchar ranges;
+};
+
 static FcConfig * FontConfig = NULL;
+static FcPattern * UIFontQuery = NULL;
+static FcPattern * UIFontPrimary = NULL;
+static FcCharSet * UIFontChars = NULL;
+static FcCharSet * UIFontRequested = NULL;
+static struct UIFontFace * UIFontFaces = NULL;
+static unsigned int UIFontFaceCount = 0;
+static LG_Lock UIFontLock;
+static bool UIFontLockInitialized = false;
+
+static void uiFontClearFaces(void)
+{
+  for (unsigned int i = 0; i < UIFontFaceCount; ++i)
+  {
+    free(UIFontFaces[i].file);
+    ImVector_ImWchar_UnInit(&UIFontFaces[i].ranges);
+  }
+
+  free(UIFontFaces);
+  UIFontFaces = NULL;
+  UIFontFaceCount = 0;
+}
+
+static void uiFontAddRanges(const ImWchar * ranges)
+{
+  for (; ranges[0]; ranges += 2)
+    for (FcChar32 c = ranges[0]; c <= (FcChar32)ranges[1]; ++c)
+      FcCharSetAddChar(UIFontChars, c);
+}
+
+static bool uiFontCharsetToRanges(
+    const FcCharSet * charset, ImVector_ImWchar * ranges)
+{
+  ImFontGlyphRangesBuilder * builder =
+    ImFontGlyphRangesBuilder_ImFontGlyphRangesBuilder();
+  if (!builder)
+    return false;
+
+  FcChar32 map[FC_CHARSET_MAP_SIZE];
+  FcChar32 next;
+  for (FcChar32 base = FcCharSetFirstPage(charset, map, &next);
+       base != FC_CHARSET_DONE;
+       base = FcCharSetNextPage(charset, map, &next))
+  {
+    for (unsigned int i = 0; i < FC_CHARSET_MAP_SIZE; ++i)
+      for (unsigned int bit = 0; bit < 32; ++bit)
+      {
+        if (!(map[i] & (UINT32_C(1) << bit)))
+          continue;
+
+        const FcChar32 c = base + i * 32 + bit;
+        if (c >= 0x20 && c <= IM_UNICODE_CODEPOINT_MAX)
+          ImFontGlyphRangesBuilder_AddChar(builder, (ImWchar)c);
+      }
+  }
+
+  ImVector_ImWchar_Init(ranges);
+  ImFontGlyphRangesBuilder_BuildRanges(builder, ranges);
+  ImFontGlyphRangesBuilder_destroy(builder);
+  return ranges->Size > 1;
+}
+
+static bool uiFontAddFace(const FcPattern * pattern, FcCharSet ** remainingPtr)
+{
+  FcCharSet * remaining = *remainingPtr;
+  FcChar8 * file;
+  FcCharSet * charset;
+  FcBool outline = FcTrue;
+
+  if (FcPatternGetString(pattern, FC_FILE, 0, &file) != FcResultMatch ||
+      FcPatternGetCharSet(pattern, FC_CHARSET, 0, &charset) != FcResultMatch)
+    return true;
+
+  if (FcPatternGetBool(pattern, FC_OUTLINE, 0, &outline) == FcResultMatch &&
+      !outline)
+    return true;
+
+  FcCharSet * covered = FcCharSetIntersect(remaining, charset);
+  if (!covered)
+    return false;
+
+  if (FcCharSetCount(covered) == 0)
+  {
+    FcCharSetDestroy(covered);
+    return true;
+  }
+
+  struct UIFontFace * faces = realloc(UIFontFaces,
+      sizeof(*UIFontFaces) * (UIFontFaceCount + 1));
+  if (!faces)
+  {
+    FcCharSetDestroy(covered);
+    return false;
+  }
+  UIFontFaces = faces;
+
+  struct UIFontFace * face = &UIFontFaces[UIFontFaceCount];
+  memset(face, 0, sizeof(*face));
+  face->file = strdup((const char *)file);
+  if (!face->file || !uiFontCharsetToRanges(covered, &face->ranges))
+  {
+    free(face->file);
+    face->file = NULL;
+    FcCharSetDestroy(covered);
+    return false;
+  }
+
+  int index = 0;
+  if (FcPatternGetInteger(pattern, FC_INDEX, 0, &index) == FcResultMatch)
+    face->index = index & 0xFFFF;
+
+  ++UIFontFaceCount;
+
+  FcCharSet * next = FcCharSetSubtract(remaining, covered);
+  FcCharSetDestroy(covered);
+  if (!next)
+    return false;
+
+  FcCharSetDestroy(remaining);
+  *remainingPtr = next;
+  return true;
+}
+
+static bool uiFontBuildFaces(ImFontAtlas * atlas)
+{
+  uiFontClearFaces();
+
+  uiFontAddRanges(ImFontAtlas_GetGlyphRangesDefault(atlas));
+  uiFontAddRanges((ImWchar[]) {
+    0x2190, 0x2193, // four directional arrows
+    0,
+  });
+
+  FcCharSet * remaining = FcCharSetCopy(UIFontChars);
+  if (!remaining)
+    return false;
+
+  if (!uiFontAddFace(UIFontPrimary, &remaining))
+    goto fail;
+
+  if (FcCharSetCount(remaining) > 0)
+  {
+    FcPattern * query = FcPatternDuplicate(UIFontQuery);
+    if (!query)
+      goto fail;
+
+    FcPatternDel(query, FC_CHARSET);
+    FcPatternAddCharSet(query, FC_CHARSET, remaining);
+
+    FcResult result;
+    FcFontSet * fonts = FcFontSort(FontConfig, query, FcTrue, NULL, &result);
+    FcPatternDestroy(query);
+    if (!fonts)
+      goto fail;
+
+    for (int i = 0; i < fonts->nfont && FcCharSetCount(remaining) > 0; ++i)
+      if (!uiFontAddFace(fonts->fonts[i], &remaining))
+      {
+        FcFontSetSortDestroy(fonts);
+        goto fail;
+      }
+
+    FcFontSetSortDestroy(fonts);
+  }
+
+  if (FcCharSetCount(remaining) > 0)
+  {
+    FcCharSet * missing = FcCharSetIntersect(remaining, UIFontRequested);
+    if (missing)
+    {
+      if (FcCharSetCount(missing) > 0)
+        DEBUG_WARN("%u requested UI glyphs have no usable outline font",
+            FcCharSetCount(missing));
+      FcCharSetDestroy(missing);
+    }
+  }
+
+  FcCharSetDestroy(remaining);
+  return UIFontFaceCount > 0;
+
+fail:
+  FcCharSetDestroy(remaining);
+  uiFontClearFaces();
+  return false;
+}
+
+static ImFont * uiFontAddSize(ImFontAtlas * atlas, float size)
+{
+  ImFont * result = NULL;
+
+  for (unsigned int i = 0; i < UIFontFaceCount; ++i)
+  {
+    ImFontConfig * config = ImFontConfig_ImFontConfig();
+    if (!config)
+      return NULL;
+
+    config->MergeMode = result != NULL;
+    config->FontNo = UIFontFaces[i].index;
+
+    ImFont * font = ImFontAtlas_AddFontFromFileTTF(atlas,
+        UIFontFaces[i].file, size, config, UIFontFaces[i].ranges.Data);
+    ImFontConfig_destroy(config);
+
+    if (!font)
+    {
+      DEBUG_WARN("Failed to add UI font face: %s", UIFontFaces[i].file);
+      continue;
+    }
+
+    if (!result)
+      result = font;
+  }
+
+  return result;
+}
 
 bool util_fileGetContents(const char * filename, char ** buffer, size_t * length)
 {
@@ -238,6 +459,25 @@ bool util_initUIFonts(void)
     return false;
   }
 
+  UIFontChars = FcCharSetCreate();
+  UIFontRequested = FcCharSetCreate();
+  if (!UIFontChars || !UIFontRequested)
+  {
+    DEBUG_ERROR("FcCharSetCreate Failed");
+    if (UIFontChars)
+      FcCharSetDestroy(UIFontChars);
+    if (UIFontRequested)
+      FcCharSetDestroy(UIFontRequested);
+    UIFontChars = NULL;
+    UIFontRequested = NULL;
+    FcConfigDestroy(FontConfig);
+    FontConfig = NULL;
+    FcFini();
+    return false;
+  }
+
+  LG_LOCK_INIT(UIFontLock);
+  UIFontLockInitialized = true;
   return true;
 }
 
@@ -264,11 +504,22 @@ char * util_getUIFont(const char * fontName)
     goto fail_parse;
   }
 
+  FcPatternDestroy(UIFontQuery);
+  FcPatternDestroy(UIFontPrimary);
+  UIFontQuery = FcPatternDuplicate(pat);
+  UIFontPrimary = FcPatternDuplicate(match);
+  if (!UIFontQuery || !UIFontPrimary)
+  {
+    DEBUG_ERROR("Failed to save the UI font pattern");
+    goto fail_match;
+  }
+
   if (FcPatternGetString(match, FC_FILE, 0, &file) == FcResultMatch)
     ttf = strdup((char *) file);
   else
     DEBUG_ERROR("Failed to locate the requested font: %s", fontName);
 
+fail_match:
   FcPatternDestroy(match);
 
 fail_parse:
@@ -276,11 +527,97 @@ fail_parse:
   return ttf;
 }
 
+bool util_uiFontAddText(const char * text)
+{
+  if (!UIFontChars || !text)
+    return false;
+
+  bool changed = false;
+  LG_LOCK(UIFontLock);
+
+  const char * pos = text;
+  while (*pos)
+  {
+    unsigned int c;
+    const int length = igImTextCharFromUtf8(&c, pos, NULL);
+    if (length <= 0)
+      break;
+    pos += length;
+
+    if (c < 0x20 || c > IM_UNICODE_CODEPOINT_MAX)
+      continue;
+
+    FcCharSetAddChar(UIFontRequested, c);
+    if (!FcCharSetHasChar(UIFontChars, c) &&
+        FcCharSetAddChar(UIFontChars, c))
+      changed = true;
+  }
+
+  LG_UNLOCK(UIFontLock);
+  return changed;
+}
+
+bool util_buildUIFontAtlas(
+    ImFontAtlas * atlas, float size, ImFont ** large)
+{
+  if (!atlas || !UIFontQuery || !UIFontPrimary || !UIFontChars)
+    return false;
+
+  bool result = false;
+  LG_LOCK(UIFontLock);
+
+  ImFontAtlas_Clear(atlas);
+  if (!uiFontBuildFaces(atlas))
+  {
+    DEBUG_ERROR("Failed to resolve UI fonts");
+    goto done;
+  }
+
+  if (!uiFontAddSize(atlas, size))
+  {
+    DEBUG_ERROR("Failed to add the primary UI font");
+    goto done;
+  }
+
+  *large = uiFontAddSize(atlas, size * 1.3f);
+  if (!*large)
+  {
+    DEBUG_ERROR("Failed to add the large UI font");
+    goto done;
+  }
+
+  result = ImFontAtlas_Build(atlas);
+
+done:
+  LG_UNLOCK(UIFontLock);
+  return result;
+}
+
 void util_freeUIFonts(void)
 {
   if (!FontConfig)
     return;
 
+  if (UIFontLockInitialized)
+    LG_LOCK(UIFontLock);
+
+  uiFontClearFaces();
+  FcCharSetDestroy(UIFontChars);
+  FcCharSetDestroy(UIFontRequested);
+  FcPatternDestroy(UIFontQuery);
+  FcPatternDestroy(UIFontPrimary);
+  UIFontChars = NULL;
+  UIFontRequested = NULL;
+  UIFontQuery = NULL;
+  UIFontPrimary = NULL;
+
+  if (UIFontLockInitialized)
+  {
+    LG_UNLOCK(UIFontLock);
+    LG_LOCK_FREE(UIFontLock);
+    UIFontLockInitialized = false;
+  }
+
   FcConfigDestroy(FontConfig);
   FontConfig = NULL;
   FcFini();