diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7746f2e889a..1a1ee41cafc 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -421,40 +421,6 @@ jobs:
       with:
         gcov: true
 
-  # Duplicates build-asan.  Please keep in sync
-  build-cxx20:
-    name: c++20
-    # Make sure we can still build on older Ubuntu
-    runs-on: ubuntu-22.04
-    env:
-      CC: "gcc"
-      CXX: "g++"
-    steps:
-    - uses: actions/setup-python@v5
-      with:
-        python-version: '3.x'
-    - uses: actions/checkout@v4
-      with:
-        submodules: true
-    - name: install ninja
-      run: sudo apt-get install ninja-build
-    - name: install v8
-      run: |
-        npm install jsvu -g
-        jsvu --os=default --engines=v8
-    - name: install Python dev dependencies
-      run: pip3 install -r requirements-dev.txt
-    - name: cmake
-      run: |
-        mkdir -p out
-        cmake -S . -B out -G Ninja -DCMAKE_INSTALL_PREFIX=out/install -DCMAKE_C_COMPILER="$CC" -DCMAKE_CXX_COMPILER="$CXX" -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_STANDARD=20
-    - name: build
-      run: cmake --build out
-    - name: test
-      run: |
-        python check.py --binaryen-bin=out/bin lit
-        python check.py --binaryen-bin=out/bin gtest
-
   # Ensures we can build in no-asserts mode (just building).
   build-noasserts:
     name: noasserts
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 11f61958d7f..0b1334ce0f5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,7 +14,9 @@ full changeset diff at the end of each section.
 
 Current Trunk
 -------------
-- The c api now has separate functions for `CallRef` and `ReturnCallRef` matching the semantics of `Call` and `ReturnCall`.
+- The c api now has separate functions for `CallRef` and `ReturnCallRef`
+  matching the semantics of `Call` and `ReturnCall`.
+- Binaryen now uses C++20, therefore requires a C++20 compliant compiler.
 
 v125
 ----
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 041793662b3..d86f8d33771 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -11,7 +11,7 @@ include(GNUInstallDirs)
 # The C++ standard whose features are required to build Binaryen.
 # Keep in sync with scripts/test/shared.py cxx_standard
 # The if condition allows embedding in a project with a higher default C++ standard set
-set(REQUIRED_CXX_STANDARD 17)
+set(REQUIRED_CXX_STANDARD 20)
 if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD ${REQUIRED_CXX_STANDARD})
 elseif(CMAKE_CXX_STANDARD LESS ${REQUIRED_CXX_STANDARD})
diff --git a/README.md b/README.md
index 529eda8ccee..d3bf66f8722 100644
--- a/README.md
+++ b/README.md
@@ -412,7 +412,9 @@ After that you can build with CMake:
 cmake . && make
 ```
 
-A C++17 compiler is required. On macOS, you need to install `cmake`, for example, via `brew install cmake`. Note that you can also use `ninja` as your generator: `cmake -G Ninja . && ninja`.
+A C++20 compiler is required. On macOS, you need to install `cmake`, for
+example, via `brew install cmake`. Note that you can also use `ninja` as your
+generator: `cmake -G Ninja . && ninja`.
 
 To avoid the gtest dependency, you can pass `-DBUILD_TESTS=OFF` to cmake.
 
diff --git a/scripts/test/shared.py b/scripts/test/shared.py
index 5116fb0c1bf..e6a0917ee24 100644
--- a/scripts/test/shared.py
+++ b/scripts/test/shared.py
@@ -26,7 +26,7 @@
 
 # The C++ standard whose features are required to build Binaryen.
 # Keep in sync with CMakeLists.txt CXX_STANDARD
-cxx_standard = 17
+cxx_standard = 20
 
 
 def parse_args(args):
diff --git a/src/ir/module-splitting.cpp b/src/ir/module-splitting.cpp
index 797314e9f34..30c8ff59aec 100644
--- a/src/ir/module-splitting.cpp
+++ b/src/ir/module-splitting.cpp
@@ -457,9 +457,9 @@ void ModuleSplitter::classifyFunctions() {
     // module since that would make them async when they may not have the JSPI
     // wrapper. Exported JSPI functions can still benefit from splitting though
     // since only the JSPI wrapper stub will remain in the primary module.
-    if (func->imported() || !configSecondaryFuncs.count(func->name) ||
+    if (func->imported() || !configSecondaryFuncs.contains(func->name) ||
         (config.jspi && ExportUtils::isExported(primary, *func)) ||
-        segmentReferrers.count(func->name)) {
+        segmentReferrers.contains(func->name)) {
       primaryFuncs.insert(func->name);
     } else {
       assert(func->name != primary.start && "The start function must be kept");
@@ -520,7 +520,7 @@ void ModuleSplitter::moveSecondaryFunctions() {
   for (auto& funcNames : config.secondaryFuncs) {
     auto secondary = initSecondary(primary);
     for (auto funcName : funcNames) {
-      if (allSecondaryFuncs.count(funcName)) {
+      if (allSecondaryFuncs.contains(funcName)) {
         auto* func = primary.getFunction(funcName);
         ModuleUtils::copyFunction(func, *secondary);
         primary.removeFunction(funcName);
@@ -567,7 +567,7 @@ void ModuleSplitter::thunkExportedSecondaryFunctions() {
   Builder builder(primary);
   for (auto& ex : primary.exports) {
     if (ex->kind != ExternalKind::Function ||
-        !allSecondaryFuncs.count(*ex->getInternalName())) {
+        !allSecondaryFuncs.contains(*ex->getInternalName())) {
       continue;
     }
     Name trampoline = getTrampoline(*ex->getInternalName());
@@ -609,7 +609,7 @@ void ModuleSplitter::indirectReferencesToSecondaryFunctions() {
       // 1. ref.func's target func is in one of the secondary modules and
       // 2. the current module is a different module (either the primary module
       //    or a different secondary module)
-      if (parent.allSecondaryFuncs.count(curr->func) &&
+      if (parent.allSecondaryFuncs.contains(curr->func) &&
           (currModule == &parent.primary ||
            parent.secondaries.at(parent.funcToSecondaryIndex.at(curr->func))
                .get() != currModule)) {
@@ -645,7 +645,7 @@ void ModuleSplitter::indirectReferencesToSecondaryFunctions() {
     std::vector<RefFunc*> relevantRefFuncs;
     for (auto* refFunc : refFuncs) {
       assert(refFunc->func == name);
-      if (!ignore.count(refFunc)) {
+      if (!ignore.contains(refFunc)) {
         relevantRefFuncs.push_back(refFunc);
       }
     }
@@ -669,7 +669,7 @@ void ModuleSplitter::indirectCallsToSecondaryFunctions() {
     CallIndirector(ModuleSplitter& parent) : parent(parent) {}
     void visitCall(Call* curr) {
       // Return if the call's target is not in one of the secondary module.
-      if (!parent.allSecondaryFuncs.count(curr->target)) {
+      if (!parent.allSecondaryFuncs.contains(curr->target)) {
         return;
       }
       // Return if the current module is the same module as the call's target,
@@ -719,12 +719,12 @@ void ModuleSplitter::exportImportCalledPrimaryFunctions() {
             : primaryFuncs(primaryFuncs),
               calledPrimaryToModules(calledPrimaryToModules) {}
           void visitCall(Call* curr) {
-            if (primaryFuncs.count(curr->target)) {
+            if (primaryFuncs.contains(curr->target)) {
               calledPrimaryToModules[curr->target].insert(getModule());
             }
           }
           void visitRefFunc(RefFunc* curr) {
-            if (primaryFuncs.count(curr->func)) {
+            if (primaryFuncs.contains(curr->func)) {
               calledPrimaryToModules[curr->func].insert(getModule());
             }
           }
@@ -760,7 +760,7 @@ void ModuleSplitter::setupTablePatching() {
       if (!ref) {
         return;
       }
-      if (!allSecondaryFuncs.count(ref->func)) {
+      if (!allSecondaryFuncs.contains(ref->func)) {
         return;
       }
       assert(table == tableManager.activeTable->name);