diff --git a/third_party/angle/src/common/utilities_unittest.cpp b/third_party/angle/src/common/utilities_unittest.cpp
index 0000000000..0000000000 100644
--- a/third_party/angle/src/common/utilities_unittest.cpp
+++ b/third_party/angle/src/common/utilities_unittest.cpp
@@ -253,6 +253,16 @@ TEST(Utilities, IndexRanges)
     EXPECT_EQ(ComputeIndexRange(b, vertices2, 2, false), gl::IndexRange(255, 255));
     EXPECT_EQ(ComputeIndexRange(b, vertices2, 3, true), gl::IndexRange(2, 2));
     EXPECT_EQ(ComputeIndexRange(b, vertices2, 3, false), gl::IndexRange(2, 255));
+
+    constexpr auto ui = gl::DrawElementsType::UnsignedInt;
+    uint32_t vertices3[] = {0u, 0xffffffffu};
+    gl::IndexRange fullUintRange = ComputeIndexRange(ui, vertices3, 2, false);
+    EXPECT_FALSE(fullUintRange.isEmpty());
+    if (!fullUintRange.isEmpty())
+    {
+        EXPECT_EQ(0u, fullUintRange.start());
+        EXPECT_EQ(0xffffffffu, fullUintRange.end());
+    }
 }
 
 }  // anonymous namespace
diff --git a/third_party/angle/src/tests/gl_tests/DrawElementsTest.cpp b/third_party/angle/src/tests/gl_tests/DrawElementsTest.cpp
index 0000000000..0000000000 100644
--- a/third_party/angle/src/tests/gl_tests/DrawElementsTest.cpp
+++ b/third_party/angle/src/tests/gl_tests/DrawElementsTest.cpp
@@ -793,6 +793,45 @@ TEST_P(WebGLDrawElementsTest, DrawElementsTypeAlignment)
     EXPECT_GL_ERROR(GL_INVALID_OPERATION);
 }
 
+// Regression test for unsigned-int index ranges that cover the full uint32_t domain.
+// With primitive restart disabled, 0xffffffff is a real WebGL1 index when
+// OES_element_index_uint is enabled.  This must not be treated as an empty range.
+TEST_P(WebGLDrawElementsTest, MixedUintMaxIndexRangeIsNotEmpty)
+{
+    ANGLE_SKIP_TEST_IF(!IsGLExtensionEnabled("GL_OES_element_index_uint"));
+
+    constexpr char kVS[] =
+        "attribute vec3 a_pos;\n"
+        "void main()\n"
+        "{\n"
+        "    gl_Position = vec4(a_pos, 1.0);\n"
+        "    gl_PointSize = 1.0;\n"
+        "}\n";
+
+    ANGLE_GL_PROGRAM(program, kVS, essl1_shaders::fs::Blue());
+
+    GLint posLocation = glGetAttribLocation(program, "a_pos");
+    ASSERT_NE(-1, posLocation);
+    glUseProgram(program);
+
+    const GLfloat vertices[] = {0.0f, 0.0f, 0.0f};
+
+    GLBuffer vertexBuffer;
+    glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+
+    glVertexAttribPointer(posLocation, 3, GL_FLOAT, GL_FALSE, 0, 0);
+    glEnableVertexAttribArray(posLocation);
+
+    GLBuffer indexBuffer;
+    const GLuint indices[] = {0u, 0xffffffffu};
+    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
+    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
+
+    glDrawElements(GL_POINTS, 2, GL_UNSIGNED_INT, nullptr);
+    EXPECT_GL_ERROR(GL_INVALID_OPERATION);
+}
+
 class WebGLDrawElementsTest3 : public WebGLDrawElementsTest
 {};
 // Test one element buffer bind to two vertexArrays and switch vertexArray should draw correctly.