diff --git a/Tests/LibEDID/TestEDID.cpp b/Tests/LibEDID/TestEDID.cpp
index aebde9f68f0..9925b0c33fe 100644
--- a/Tests/LibEDID/TestEDID.cpp
+++ b/Tests/LibEDID/TestEDID.cpp
@@ -366,6 +366,148 @@ TEST_CASE(edid2)
     }
 }
 
+// This EDID has extension maps
+static const u8 edid_extension_maps[] = {
+    0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x4d, 0x29, 0x48, 0x44,
+    0x01, 0x00, 0x00, 0x00, 0x0a, 0x0d, 0x01, 0x03, 0x80, 0x50, 0x2d, 0x78,
+    0x0a, 0x0d, 0xc9, 0xa0, 0x57, 0x47, 0x98, 0x27, 0x12, 0x48, 0x4c, 0x20,
+    0x00, 0x00, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x1d, 0x80, 0x18, 0x71, 0x1c,
+    0x16, 0x20, 0x58, 0x2c, 0x25, 0x00, 0x20, 0xc2, 0x31, 0x00, 0x00, 0x9e,
+    0x8c, 0x0a, 0xd0, 0x8a, 0x20, 0xe0, 0x2d, 0x10, 0x10, 0x3e, 0x96, 0x00,
+    0x13, 0x8e, 0x21, 0x00, 0x00, 0x18, 0x00, 0x00, 0x00, 0xfc, 0x00, 0x48,
+    0x44, 0x4d, 0x49, 0x20, 0x54, 0x56, 0x0a, 0x20, 0x20, 0x20, 0x20, 0x20,
+    0x00, 0x00, 0x00, 0xfd, 0x00, 0x3b, 0x3d, 0x0f, 0x2e, 0x08, 0x02, 0x00,
+    0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x03, 0xf1, 0xf0, 0x02, 0x02, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x0c, 0x02, 0x03, 0x1e, 0xf1, 0x4a, 0x85, 0x04, 0x10,
+    0x02, 0x01, 0x06, 0x14, 0x12, 0x16, 0x13, 0x23, 0x09, 0x07, 0x07, 0x83,
+    0x01, 0x00, 0x00, 0x66, 0x03, 0x0c, 0x00, 0x10, 0x00, 0x80, 0x01, 0x1d,
+    0x00, 0x72, 0x51, 0xd0, 0x1e, 0x20, 0x6e, 0x28, 0x55, 0x00, 0xc4, 0x8e,
+    0x21, 0x00, 0x00, 0x1e, 0xd6, 0x09, 0x80, 0xa0, 0x20, 0xe0, 0x2d, 0x10,
+    0x10, 0x60, 0x22, 0x00, 0x12, 0x8e, 0x21, 0x08, 0x08, 0x18, 0x8c, 0x0a,
+    0xd0, 0x90, 0x20, 0x40, 0x31, 0x20, 0x0c, 0x40, 0x55, 0x00, 0xc4, 0x8e,
+    0x21, 0x00, 0x00, 0x18, 0x01, 0x1d, 0x80, 0xd0, 0x72, 0x1c, 0x16, 0x20,
+    0x10, 0x2c, 0x25, 0x80, 0xc4, 0x8e, 0x21, 0x00, 0x00, 0x9e, 0x8c, 0x0a,
+    0xa0, 0x14, 0x51, 0xf0, 0x16, 0x00, 0x26, 0x7c, 0x43, 0x00, 0x13, 0x8e,
+    0x21, 0x00, 0x00, 0x98, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf5,
+    0x02, 0x03, 0x04, 0xf1, 0xf3, 0x39, 0x80, 0x18, 0x71, 0x38, 0x2d, 0x40,
+    0x58, 0x2c, 0x45, 0x00, 0xc4, 0x8e, 0x21, 0x00, 0x00, 0x1e, 0x8c, 0x0a,
+    0xa0, 0x20, 0x51, 0x20, 0x18, 0x10, 0x18, 0x7e, 0x23, 0x00, 0xc4, 0x8e,
+    0x21, 0x00, 0x00, 0x98, 0x01, 0x1d, 0x00, 0xbc, 0x52, 0xd0, 0x1e, 0x20,
+    0xb8, 0x28, 0x55, 0x40, 0xc4, 0x8e, 0x21, 0x00, 0x00, 0x1e, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xdf
+};
+
+TEST_CASE(edid_extension_maps)
+{
+    auto edid_load_result = EDID::Parser::from_bytes({ edid_extension_maps, sizeof(edid_extension_maps) });
+    EXPECT(!edid_load_result.is_error());
+    auto edid = edid_load_result.release_value();
+    EXPECT(edid.legacy_manufacturer_id() == "SII");
+
+    {
+        static constexpr struct {
+            unsigned block_id;
+            unsigned width;
+            unsigned height;
+            unsigned refresh_rate;
+        } expected_detailed_timings[] = {
+            { 0, 1920, 1080, 60 },
+            { 0, 720, 480, 60 },
+            { 2, 1280, 720, 60 },
+            { 2, 640, 480, 60 },
+            { 2, 720, 576, 50 },
+            { 2, 1920, 1080, 50 },
+            { 2, 1440, 480, 60 },
+            { 3, 1920, 1080, 60 },
+            { 3, 1440, 576, 50 },
+            { 3, 1280, 720, 50 }
+        };
+        static constexpr size_t expected_detailed_timings_count = sizeof(expected_detailed_timings) / sizeof(expected_detailed_timings[0]);
+        size_t detailed_timings_found = 0;
+        auto result = edid.for_each_detailed_timing([&](auto& detailed_timing, unsigned block_id) {
+            EXPECT(detailed_timings_found < expected_detailed_timings_count);
+            auto& expected_timings = expected_detailed_timings[detailed_timings_found];
+            EXPECT(block_id == expected_timings.block_id);
+            EXPECT(detailed_timing.horizontal_addressable_pixels() == expected_timings.width);
+            EXPECT(detailed_timing.vertical_addressable_lines() == expected_timings.height);
+            EXPECT(detailed_timing.refresh_rate().lround() == expected_timings.refresh_rate);
+            detailed_timings_found++;
+            return IterationDecision::Continue;
+        });
+        EXPECT(!result.is_error());
+        EXPECT(result.value() == IterationDecision::Continue);
+        EXPECT(detailed_timings_found == expected_detailed_timings_count);
+    }
+}
+
+static const u8 edid_1_0[] = {
+    0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x34, 0x38, 0xc2, 0x0b,
+    0x7b, 0x00, 0x00, 0x00, 0x0f, 0x0a, 0x01, 0x00, 0x28, 0x20, 0x18, 0x32,
+    0xe8, 0x7e, 0x4e, 0x9e, 0x57, 0x45, 0x98, 0x24, 0x10, 0x47, 0x4f, 0xa4,
+    0x42, 0x01, 0x31, 0x59, 0x45, 0x59, 0x61, 0x59, 0x71, 0x4f, 0x81, 0x80,
+    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0xf9, 0x15, 0x20, 0xf8, 0x30, 0x58,
+    0x1f, 0x20, 0x20, 0x40, 0x13, 0x00, 0x40, 0xf0, 0x10, 0x00, 0x00, 0x1e,
+    0xa4, 0x1a, 0x20, 0x10, 0x31, 0x58, 0x24, 0x20, 0x2f, 0x55, 0x33, 0x00,
+    0x40, 0xf0, 0x10, 0x00, 0x00, 0x1e, 0x30, 0x2a, 0x00, 0x98, 0x51, 0x00,
+    0x2a, 0x40, 0x30, 0x70, 0x13, 0x00, 0x40, 0xf0, 0x10, 0x00, 0x00, 0x1e,
+    0xea, 0x24, 0x00, 0x60, 0x41, 0x00, 0x28, 0x30, 0x30, 0x60, 0x13, 0x00,
+    0x40, 0xf0, 0x10, 0x00, 0x00, 0x1e, 0x00, 0x72
+};
+
+TEST_CASE(edid_1_0)
+{
+    auto edid_load_result = EDID::Parser::from_bytes({ edid_1_0, sizeof(edid_1_0) });
+    EXPECT(!edid_load_result.is_error());
+    auto edid = edid_load_result.release_value();
+    EXPECT(edid.legacy_manufacturer_id() == "MAX");
+    EXPECT(edid.serial_number() == 123);
+
+    {
+        static constexpr struct {
+            unsigned block_id;
+            unsigned width;
+            unsigned height;
+            unsigned refresh_rate;
+        } expected_detailed_timings[] = {
+            { 0, 800, 600, 85 },
+            { 0, 800, 600, 100 },
+            { 0, 1280, 1024, 60 },
+            { 0, 1024, 768, 85 }
+        };
+        static constexpr size_t expected_detailed_timings_count = sizeof(expected_detailed_timings) / sizeof(expected_detailed_timings[0]);
+        size_t detailed_timings_found = 0;
+        auto result = edid.for_each_detailed_timing([&](auto& detailed_timing, unsigned block_id) {
+            EXPECT(detailed_timings_found < expected_detailed_timings_count);
+            auto& expected_timings = expected_detailed_timings[detailed_timings_found];
+            EXPECT(block_id == expected_timings.block_id);
+            EXPECT(detailed_timing.horizontal_addressable_pixels() == expected_timings.width);
+            EXPECT(detailed_timing.vertical_addressable_lines() == expected_timings.height);
+            EXPECT(detailed_timing.refresh_rate().lround() == expected_timings.refresh_rate);
+            detailed_timings_found++;
+            return IterationDecision::Continue;
+        });
+        EXPECT(!result.is_error());
+        EXPECT(result.value() == IterationDecision::Continue);
+        EXPECT(detailed_timings_found == expected_detailed_timings_count);
+    }
+}
+
 TEST_CASE(dmt_find_std_id)
 {
     auto* dmt = EDID::DMT::find_timing_by_std_id(0xd1, 0xf);
diff --git a/Userland/Libraries/LibEDID/EDID.cpp b/Userland/Libraries/LibEDID/EDID.cpp
index 7c013c9eaeb..81c8ca4215b 100644
--- a/Userland/Libraries/LibEDID/EDID.cpp
+++ b/Userland/Libraries/LibEDID/EDID.cpp
@@ -141,7 +141,7 @@ struct [[gnu::packed]] EDID {
     u8 checksum;
 };
 
-enum ExtensionBlockTag : u8 {
+enum class ExtensionBlockTag : u8 {
     CEA_861 = 0x2,
     VideoTimingBlock = 0x10,
     DisplayInformation = 0x40,
@@ -220,8 +220,10 @@ public:
     ErrorOr<IterationDecision> for_each_dtd(Function<IterationDecision(Parser::DetailedTiming const&)> callback) const
     {
         u8 dtd_start = m_edid.read_host(&m_block->cea861extension.dtd_start_offset);
-        if (dtd_start <= 4)
+        if (dtd_start < 4) {
+            // dtd_start == 4 means there are no data blocks, but there are still DTDs
             return IterationDecision::Continue;
+        }
 
         if (dtd_start > offsetof(Definitions::ExtensionBlock, checksum) - sizeof(Definitions::DetailedTiming))
             return Error::from_string_literal("CEA 861 extension block has invalid DTD list"sv);
@@ -488,35 +490,39 @@ ErrorOr<IterationDecision> Parser::for_each_extension_block(Function<IterationDe
     if (sizeof(Definitions::EDID) + (size_t)raw_extension_block_count * sizeof(Definitions::ExtensionBlock) > m_bytes.size())
         return Error::from_string_literal("Truncated EDID");
 
-    auto validate_block_checksum = [&](Definitions::ExtensionBlock const& extension_map) {
+    auto validate_block_checksum = [&](Definitions::ExtensionBlock const& block) {
         u8 checksum = 0x0;
-        auto* bytes = (u8 const*)&extension_map;
-        for (size_t i = 0; i < sizeof(extension_map); i++)
+        auto* bytes = (u8 const*)&block;
+        for (size_t i = 0; i < sizeof(block); i++)
             checksum += bytes[i];
 
         return checksum == 0;
     };
 
-    size_t offset = sizeof(Definitions::EDID);
-    auto* raw_extension_blocks = (Definitions::ExtensionBlock const*)(m_bytes.data() + offset);
+    auto* raw_extension_blocks = (Definitions::ExtensionBlock const*)(m_bytes.data() + sizeof(Definitions::EDID));
     Definitions::ExtensionBlock const* current_extension_map = nullptr;
+
+    unsigned raw_index = 0;
     if (m_revision <= 3) {
         if (raw_extension_block_count > 1) {
             current_extension_map = &raw_extension_blocks[0];
-            if (read_host(&current_extension_map->tag) != Definitions::ExtensionBlockTag::ExtensionBlockMap)
+            raw_index++;
+            if (read_host(&current_extension_map->tag) != (u8)Definitions::ExtensionBlockTag::ExtensionBlockMap)
                 return Error::from_string_literal("Did not find extension map at block 1"sv);
             if (!validate_block_checksum(*current_extension_map))
                 return Error::from_string_literal("Extension block map checksum mismatch"sv);
         }
-    } else if (read_host(&raw_extension_blocks[0].tag) == Definitions::ExtensionBlockTag::ExtensionBlockMap) {
+    } else if (read_host(&raw_extension_blocks[0].tag) == (u8)Definitions::ExtensionBlockTag::ExtensionBlockMap) {
         current_extension_map = &raw_extension_blocks[0];
+        raw_index++;
     }
 
-    for (unsigned raw_index = 0; raw_index < raw_extension_block_count; raw_index++) {
+    for (; raw_index < raw_extension_block_count; raw_index++) {
         auto& raw_block = raw_extension_blocks[raw_index];
         u8 tag = read_host(&raw_block.tag);
+
         if (current_extension_map && raw_index == 127) {
-            if (tag != Definitions::ExtensionBlockTag::ExtensionBlockMap)
+            if (tag != (u8)Definitions::ExtensionBlockTag::ExtensionBlockMap)
                 return Error::from_string_literal("Did not find extension map at block 128"sv);
             current_extension_map = &raw_extension_blocks[127];
             if (!validate_block_checksum(*current_extension_map))
@@ -524,17 +530,16 @@ ErrorOr<IterationDecision> Parser::for_each_extension_block(Function<IterationDe
             continue;
         }
 
-        if (tag == Definitions::ExtensionBlockTag::ExtensionBlockMap)
+        if (tag == (u8)Definitions::ExtensionBlockTag::ExtensionBlockMap)
             return Error::from_string_literal("Unexpected extension map encountered"sv);
 
         if (!validate_block_checksum(raw_block))
             return Error::from_string_literal("Extension block checksum mismatch"sv);
 
+        size_t offset = (u8 const*)&raw_block - m_bytes.data();
         IterationDecision decision = callback(raw_index + 1, tag, raw_block.block.revision, m_bytes.slice(offset, sizeof(Definitions::ExtensionBlock)));
         if (decision != IterationDecision::Continue)
             return decision;
-
-        offset += sizeof(Definitions::ExtensionBlock);
     }
     return IterationDecision::Continue;
 }
@@ -1033,7 +1038,7 @@ ErrorOr<IterationDecision> Parser::for_each_detailed_timing(Function<IterationDe
 
     Optional<Error> extension_error;
     auto result = for_each_extension_block([&](u8 block_id, u8 tag, u8, ReadonlyBytes bytes) {
-        if (tag != Definitions::ExtensionBlockTag::CEA_861)
+        if (tag != (u8)Definitions::ExtensionBlockTag::CEA_861)
             return IterationDecision::Continue;
 
         CEA861ExtensionBlock cea861(*this, (Definitions::ExtensionBlock const*)bytes.data());
@@ -1077,7 +1082,7 @@ ErrorOr<IterationDecision> Parser::for_each_short_video_descriptor(Function<Iter
 {
     Optional<Error> extension_error;
     auto result = for_each_extension_block([&](u8 block_id, u8 tag, u8, ReadonlyBytes bytes) {
-        if (tag != Definitions::ExtensionBlockTag::CEA_861)
+        if (tag != (u8)Definitions::ExtensionBlockTag::CEA_861)
             return IterationDecision::Continue;
 
         CEA861ExtensionBlock cea861(*this, (Definitions::ExtensionBlock const*)bytes.data());
@@ -1113,7 +1118,7 @@ ErrorOr<IterationDecision> Parser::for_each_display_descriptor(Function<Iteratio
 
     Optional<Error> extension_error;
     auto result = for_each_extension_block([&](u8, u8 tag, u8, ReadonlyBytes bytes) {
-        if (tag != Definitions::ExtensionBlockTag::CEA_861)
+        if (tag != (u8)Definitions::ExtensionBlockTag::CEA_861)
             return IterationDecision::Continue;
 
         CEA861ExtensionBlock cea861(*this, (Definitions::ExtensionBlock const*)bytes.data());