diff --git a/Libraries/LibUnicode/Segmenter.cpp b/Libraries/LibUnicode/Segmenter.cpp
index ec73eb1e7b8..db66f9e5516 100644
--- a/Libraries/LibUnicode/Segmenter.cpp
+++ b/Libraries/LibUnicode/Segmenter.cpp
@@ -87,13 +87,15 @@ public:
     virtual Optional<size_t> previous_boundary(size_t boundary, Inclusive inclusive) override
     {
         auto icu_boundary = align_boundary(boundary);
+        if (!icu_boundary.has_value())
+            return {};
 
         if (inclusive == Inclusive::Yes) {
-            if (static_cast<bool>(m_segmenter->isBoundary(icu_boundary)))
-                return static_cast<size_t>(icu_boundary);
+            if (static_cast<bool>(m_segmenter->isBoundary(*icu_boundary)))
+                return static_cast<size_t>(*icu_boundary);
         }
 
-        if (auto index = m_segmenter->preceding(icu_boundary); index != icu::BreakIterator::DONE)
+        if (auto index = m_segmenter->preceding(*icu_boundary); index != icu::BreakIterator::DONE)
             return static_cast<size_t>(index);
 
         return {};
@@ -102,13 +104,15 @@ public:
     virtual Optional<size_t> next_boundary(size_t boundary, Inclusive inclusive) override
     {
         auto icu_boundary = align_boundary(boundary);
+        if (!icu_boundary.has_value())
+            return {};
 
         if (inclusive == Inclusive::Yes) {
-            if (static_cast<bool>(m_segmenter->isBoundary(icu_boundary)))
-                return static_cast<size_t>(icu_boundary);
+            if (static_cast<bool>(m_segmenter->isBoundary(*icu_boundary)))
+                return static_cast<size_t>(*icu_boundary);
         }
 
-        if (auto index = m_segmenter->following(icu_boundary); index != icu::BreakIterator::DONE)
+        if (auto index = m_segmenter->following(*icu_boundary); index != icu::BreakIterator::DONE)
             return static_cast<size_t>(index);
 
         return {};
@@ -173,19 +177,25 @@ public:
     }
 
 private:
-    i32 align_boundary(size_t boundary)
+    Optional<i32> align_boundary(size_t boundary)
     {
         auto icu_boundary = static_cast<i32>(boundary);
 
         return m_segmented_text.visit(
-            [&](String const& text) {
+            [&](String const& text) -> Optional<i32> {
+                if (boundary >= text.byte_count())
+                    return {};
+
                 U8_SET_CP_START(text.bytes().data(), 0, icu_boundary);
                 return icu_boundary;
             },
-            [&](icu::UnicodeString const& text) {
+            [&](icu::UnicodeString const& text) -> Optional<i32> {
+                if (icu_boundary >= text.length())
+                    return {};
+
                 return text.getChar32Start(icu_boundary);
             },
-            [](Empty) -> i32 { VERIFY_NOT_REACHED(); });
+            [](Empty) -> Optional<i32> { VERIFY_NOT_REACHED(); });
     }
 
     void for_each_boundary(SegmentationCallback callback)
diff --git a/Tests/LibUnicode/TestSegmenter.cpp b/Tests/LibUnicode/TestSegmenter.cpp
index 403c428f66b..d40ea82cebf 100644
--- a/Tests/LibUnicode/TestSegmenter.cpp
+++ b/Tests/LibUnicode/TestSegmenter.cpp
@@ -9,6 +9,7 @@
 #include <AK/Array.h>
 #include <AK/String.h>
 #include <AK/StringView.h>
+#include <AK/Utf16View.h>
 #include <AK/Vector.h>
 #include <LibUnicode/Segmenter.h>
 
@@ -126,3 +127,31 @@ TEST_CASE(word_segmentation)
         "The quick (“brown”) fox can’t jump 32.3 feet, right?"sv,
         { 0u, 3u, 4u, 9u, 10u, 11u, 14u, 19u, 22u, 23u, 24u, 27u, 28u, 35u, 36u, 40u, 41u, 45u, 46u, 50u, 51u, 52u, 57u, 58u });
 }
+
+TEST_CASE(out_of_bounds)
+{
+    {
+        auto text = "foo"_string;
+
+        auto segmenter = Unicode::Segmenter::create(Unicode::SegmenterGranularity::Word);
+        segmenter->set_segmented_text(text);
+
+        auto result = segmenter->previous_boundary(text.byte_count());
+        EXPECT(!result.has_value());
+
+        result = segmenter->next_boundary(text.byte_count());
+        EXPECT(!result.has_value());
+    }
+    {
+        auto text = MUST(AK::utf8_to_utf16("foo"sv));
+
+        auto segmenter = Unicode::Segmenter::create(Unicode::SegmenterGranularity::Word);
+        segmenter->set_segmented_text(Utf16View { text });
+
+        auto result = segmenter->previous_boundary(text.size());
+        EXPECT(!result.has_value());
+
+        result = segmenter->next_boundary(text.size());
+        EXPECT(!result.has_value());
+    }
+}