diff --git a/lib/fizzy/capi.cpp b/lib/fizzy/capi.cpp
index 41966e7c5..82c126109 100644
--- a/lib/fizzy/capi.cpp
+++ b/lib/fizzy/capi.cpp
@@ -112,7 +112,7 @@ inline fizzy::ExecutionResult unwrap(const FizzyExecutionResult& result) noexcep
 }
 
 fizzy::ExecutionResult unwrapped_external_function(
-    void* context, fizzy::Instance& instance, const fizzy::Value* args, int depth)
+    void* context, fizzy::Instance& instance, const fizzy::Value* args, int depth) noexcept
 {
     const auto* c_external_function = static_cast<const FizzyExternalFunction*>(context);
     return unwrap(c_external_function->function(
diff --git a/lib/fizzy/execute.cpp b/lib/fizzy/execute.cpp
index 4aecd44ef..bd78c7e36 100644
--- a/lib/fizzy/execute.cpp
+++ b/lib/fizzy/execute.cpp
@@ -475,7 +475,7 @@ void branch(const Code& code, OperandStack& stack, const uint8_t*& pc, uint32_t
 }
 
 inline bool invoke_function(const FuncType& func_type, uint32_t func_idx, Instance& instance,
-    OperandStack& stack, int depth)
+    OperandStack& stack, int depth) noexcept
 {
     const auto num_args = func_type.inputs.size();
     assert(stack.size() >= num_args);
@@ -501,7 +501,7 @@ inline bool invoke_function(const FuncType& func_type, uint32_t func_idx, Instan
 
 }  // namespace
 
-ExecutionResult execute(Instance& instance, FuncIdx func_idx, const Value* args, int depth)
+ExecutionResult execute(Instance& instance, FuncIdx func_idx, const Value* args, int depth) noexcept
 {
     assert(depth >= 0);
     if (depth > CallStackLimit)
diff --git a/lib/fizzy/execute.hpp b/lib/fizzy/execute.hpp
index 6e955eab2..6c1f2c219 100644
--- a/lib/fizzy/execute.hpp
+++ b/lib/fizzy/execute.hpp
@@ -37,10 +37,11 @@ constexpr ExecutionResult Void{true};
 constexpr ExecutionResult Trap{false};
 
 // Execute a function on an instance.
-ExecutionResult execute(Instance& instance, FuncIdx func_idx, const Value* args, int depth = 0);
+ExecutionResult execute(
+    Instance& instance, FuncIdx func_idx, const Value* args, int depth = 0) noexcept;
 
 inline ExecutionResult execute(
-    Instance& instance, FuncIdx func_idx, std::initializer_list<Value> args)
+    Instance& instance, FuncIdx func_idx, std::initializer_list<Value> args) noexcept
 {
     assert(args.size() == instance.module->get_function_type(func_idx).inputs.size());
     return execute(instance, func_idx, args.begin());
diff --git a/lib/fizzy/instantiate.cpp b/lib/fizzy/instantiate.cpp
index 94cd4dfac..02f8aa884 100644
--- a/lib/fizzy/instantiate.cpp
+++ b/lib/fizzy/instantiate.cpp
@@ -427,7 +427,7 @@ std::optional<ExportedFunction> find_exported_function(Instance& instance, std::
         return std::nullopt;
 
     const auto idx = *opt_index;
-    auto func = [](void* context, fizzy::Instance&, const Value* args, int depth) {
+    auto func = [](void* context, fizzy::Instance&, const Value* args, int depth) noexcept {
         auto* instance_and_idx = static_cast<std::pair<Instance*, FuncIdx>*>(context);
         return execute(*instance_and_idx->first, instance_and_idx->second, args, depth);
     };
diff --git a/lib/fizzy/instantiate.hpp b/lib/fizzy/instantiate.hpp
index 323113a55..377b37dff 100644
--- a/lib/fizzy/instantiate.hpp
+++ b/lib/fizzy/instantiate.hpp
@@ -22,7 +22,8 @@ namespace fizzy
 struct ExecutionResult;
 struct Instance;
 
-using ExternalFunctionPtr = ExecutionResult (*)(void* context, Instance&, const Value*, int depth);
+using ExternalFunctionPtr = ExecutionResult (*)(
+    void* context, Instance&, const Value*, int depth) noexcept;
 
 struct ExternalFunction
 {
diff --git a/test/unittests/api_test.cpp b/test/unittests/api_test.cpp
index 5764347b3..f9ed805ef 100644
--- a/test/unittests/api_test.cpp
+++ b/test/unittests/api_test.cpp
@@ -16,12 +16,12 @@ using namespace fizzy::test;
 namespace
 {
 template <int N>
-ExecutionResult function_returning_value(void*, Instance&, const Value*, int)
+ExecutionResult function_returning_value(void*, Instance&, const Value*, int) noexcept
 {
     return Value{N};
 }
 
-ExecutionResult function_returning_void(void*, Instance&, const Value*, int)
+ExecutionResult function_returning_void(void*, Instance&, const Value*, int) noexcept
 {
     return Void;
 }
@@ -272,7 +272,9 @@ TEST(api, find_exported_function)
         "0061736d010000000105016000017f021001087370656374657374036261720000040401700000050401010102"
         "0606017f0041000b07170403666f6f000001670300037461620100036d656d0200");
 
-    auto bar = [](void*, Instance&, const Value*, int) -> ExecutionResult { return Value{42}; };
+    auto bar = [](void*, Instance&, const Value*, int) noexcept -> ExecutionResult {
+        return Value{42};
+    };
     const auto bar_type = FuncType{{}, {ValType::i32}};
 
     auto instance_reexported_function =
diff --git a/test/unittests/execute_call_test.cpp b/test/unittests/execute_call_test.cpp
index b02cd82f3..624d44792 100644
--- a/test/unittests/execute_call_test.cpp
+++ b/test/unittests/execute_call_test.cpp
@@ -277,7 +277,7 @@ TEST(execute_call, imported_function_call)
 
     const auto module = parse(wasm);
 
-    constexpr auto host_foo = [](void*, Instance&, const Value*, int) -> ExecutionResult {
+    constexpr auto host_foo = [](void*, Instance&, const Value*, int) noexcept -> ExecutionResult {
         return Value{42};
     };
     const auto host_foo_type = module->typesec[0];
@@ -304,7 +304,7 @@ TEST(execute_call, imported_function_call_with_arguments)
 
     const auto module = parse(wasm);
 
-    auto host_foo = [](void*, Instance&, const Value* args, int) -> ExecutionResult {
+    auto host_foo = [](void*, Instance&, const Value* args, int) noexcept -> ExecutionResult {
         return Value{as_uint32(args[0]) * 2};
     };
     const auto host_foo_type = module->typesec[0];
@@ -348,11 +348,12 @@ TEST(execute_call, imported_functions_call_indirect)
     ASSERT_EQ(module->importsec.size(), 2);
     ASSERT_EQ(module->codesec.size(), 2);
 
-    constexpr auto sqr = [](void*, Instance&, const Value* args, int) -> ExecutionResult {
+    constexpr auto sqr = [](void*, Instance&, const Value* args, int) noexcept -> ExecutionResult {
         const auto x = as_uint32(args[0]);
         return Value{uint64_t{x} * uint64_t{x}};
     };
-    constexpr auto isqrt = [](void*, Instance&, const Value* args, int) -> ExecutionResult {
+    constexpr auto isqrt = [](void*, Instance&, const Value* args,
+                               int) noexcept -> ExecutionResult {
         const auto x = as_uint32(args[0]);
         return Value{(11 + uint64_t{x} / 11) / 2};
     };
@@ -571,7 +572,8 @@ TEST(execute_call, call_imported_infinite_recursion)
     const auto wasm = from_hex("0061736d010000000105016000017f020b01036d6f6403666f6f0000");
 
     const auto module = parse(wasm);
-    auto host_foo = [](void*, Instance& instance, const Value* args, int depth) -> ExecutionResult {
+    auto host_foo = [](void*, Instance& instance, const Value* args,
+                        int depth) noexcept -> ExecutionResult {
         EXPECT_LE(depth, MaxDepth);
         return execute(instance, 0, args, depth + 1);
     };
@@ -594,7 +596,8 @@ TEST(execute_call, call_via_imported_infinite_recursion)
         "0061736d010000000105016000017f020b01036d6f6403666f6f0000030201000a0601040010000b");
 
     const auto module = parse(wasm);
-    auto host_foo = [](void*, Instance& instance, const Value* args, int depth) -> ExecutionResult {
+    auto host_foo = [](void*, Instance& instance, const Value* args,
+                        int depth) noexcept -> ExecutionResult {
         // Function $f will increase depth. This means each iteration goes 2 steps deeper.
         EXPECT_LE(depth, MaxDepth - 1);
         return execute(instance, 1, args, depth + 1);
@@ -614,7 +617,8 @@ TEST(execute_call, call_imported_max_depth_recursion)
     const auto wasm = from_hex("0061736d010000000105016000017f020b01036d6f6403666f6f0000");
 
     const auto module = parse(wasm);
-    auto host_foo = [](void*, Instance& instance, const Value* args, int depth) -> ExecutionResult {
+    auto host_foo = [](void*, Instance& instance, const Value* args,
+                        int depth) noexcept -> ExecutionResult {
         if (depth == MaxDepth)
             return Value{uint32_t{1}};  // Terminate recursion on the max depth.
         return execute(instance, 0, args, depth + 1);
@@ -638,7 +642,8 @@ TEST(execute_call, call_via_imported_max_depth_recursion)
         "0061736d010000000105016000017f020b01036d6f6403666f6f0000030201000a0601040010000b");
 
     const auto module = parse(wasm);
-    auto host_foo = [](void*, Instance& instance, const Value* args, int depth) -> ExecutionResult {
+    auto host_foo = [](void*, Instance& instance, const Value* args,
+                        int depth) noexcept -> ExecutionResult {
         // Function $f will increase depth. This means each iteration goes 2 steps deeper.
         if (depth == (MaxDepth - 1))
             return Value{uint32_t{1}};  // Terminate recursion on the max depth.
diff --git a/test/unittests/execute_test.cpp b/test/unittests/execute_test.cpp
index a67019586..22d929fdc 100644
--- a/test/unittests/execute_test.cpp
+++ b/test/unittests/execute_test.cpp
@@ -774,7 +774,8 @@ TEST(execute, imported_function)
     const auto module = parse(wasm);
     ASSERT_EQ(module->typesec.size(), 1);
 
-    constexpr auto host_foo = [](void*, Instance&, const Value* args, int) -> ExecutionResult {
+    constexpr auto host_foo = [](void*, Instance&, const Value* args,
+                                  int) noexcept -> ExecutionResult {
         return Value{as_uint32(args[0]) + as_uint32(args[1])};
     };
 
@@ -794,10 +795,12 @@ TEST(execute, imported_two_functions)
     const auto module = parse(wasm);
     ASSERT_EQ(module->typesec.size(), 1);
 
-    constexpr auto host_foo1 = [](void*, Instance&, const Value* args, int) -> ExecutionResult {
+    constexpr auto host_foo1 = [](void*, Instance&, const Value* args,
+                                   int) noexcept -> ExecutionResult {
         return Value{as_uint32(args[0]) + as_uint32(args[1])};
     };
-    constexpr auto host_foo2 = [](void*, Instance&, const Value* args, int) -> ExecutionResult {
+    constexpr auto host_foo2 = [](void*, Instance&, const Value* args,
+                                   int) noexcept -> ExecutionResult {
         return Value{as_uint32(args[0]) * as_uint32(args[1])};
     };
 
@@ -821,10 +824,12 @@ TEST(execute, imported_functions_and_regular_one)
         "0061736d0100000001070160027f7f017f021702036d6f6404666f6f310000036d6f6404666f6f320000030201"
         "000a0901070041aa80a8010b");
 
-    constexpr auto host_foo1 = [](void*, Instance&, const Value* args, int) -> ExecutionResult {
+    constexpr auto host_foo1 = [](void*, Instance&, const Value* args,
+                                   int) noexcept -> ExecutionResult {
         return Value{as_uint32(args[0]) + as_uint32(args[1])};
     };
-    constexpr auto host_foo2 = [](void*, Instance&, const Value* args, int) -> ExecutionResult {
+    constexpr auto host_foo2 = [](void*, Instance&, const Value* args,
+                                   int) noexcept -> ExecutionResult {
         return Value{as_uint32(args[0]) * as_uint32(args[1])};
     };
 
@@ -851,10 +856,12 @@ TEST(execute, imported_two_functions_different_type)
         "0061736d01000000010c0260027f7f017f60017e017e021702036d6f6404666f6f310000036d6f6404666f6f32"
         "0001030201010a0901070042aa80a8010b");
 
-    constexpr auto host_foo1 = [](void*, Instance&, const Value* args, int) -> ExecutionResult {
+    constexpr auto host_foo1 = [](void*, Instance&, const Value* args,
+                                   int) noexcept -> ExecutionResult {
         return Value{as_uint32(args[0]) + as_uint32(args[1])};
     };
-    constexpr auto host_foo2 = [](void*, Instance&, const Value* args, int) -> ExecutionResult {
+    constexpr auto host_foo2 = [](void*, Instance&, const Value* args,
+                                   int) noexcept -> ExecutionResult {
         return Value{args[0].i64 * args[0].i64};
     };
 
@@ -875,7 +882,7 @@ TEST(execute, imported_function_traps)
     */
     const auto wasm = from_hex("0061736d0100000001070160027f7f017f020b01036d6f6403666f6f0000");
 
-    constexpr auto host_foo = [](void*, Instance&, const Value*, int) -> ExecutionResult {
+    constexpr auto host_foo = [](void*, Instance&, const Value*, int) noexcept -> ExecutionResult {
         return Trap;
     };
 
diff --git a/test/unittests/instantiate_test.cpp b/test/unittests/instantiate_test.cpp
index 45c8260a2..02f3c8588 100644
--- a/test/unittests/instantiate_test.cpp
+++ b/test/unittests/instantiate_test.cpp
@@ -32,7 +32,7 @@ TEST(instantiate, imported_functions)
     const auto bin = from_hex("0061736d0100000001060160017f017f020b01036d6f6403666f6f0000");
     const auto module = parse(bin);
 
-    auto host_foo = [](void*, Instance&, const Value*, int) { return Trap; };
+    auto host_foo = [](void*, Instance&, const Value*, int) noexcept { return Trap; };
     auto instance = instantiate(*module, {{host_foo, nullptr, module->typesec[0]}});
 
     ASSERT_EQ(instance->imported_functions.size(), 1);
@@ -53,8 +53,8 @@ TEST(instantiate, imported_functions_multiple)
         "0061736d0100000001090260017f017f600000021702036d6f6404666f6f310000036d6f6404666f6f320001");
     const auto module = parse(bin);
 
-    auto host_foo1 = [](void*, Instance&, const Value*, int) { return Trap; };
-    auto host_foo2 = [](void*, Instance&, const Value*, int) { return Trap; };
+    auto host_foo1 = [](void*, Instance&, const Value*, int) noexcept { return Trap; };
+    auto host_foo2 = [](void*, Instance&, const Value*, int) noexcept { return Trap; };
     auto instance = instantiate(*module,
         {{host_foo1, nullptr, module->typesec[0]}, {host_foo2, nullptr, module->typesec[1]}});
 
@@ -87,7 +87,7 @@ TEST(instantiate, imported_function_wrong_type)
     */
     const auto bin = from_hex("0061736d0100000001060160017f017f020b01036d6f6403666f6f0000");
 
-    auto host_foo = [](void*, Instance&, const Value*, int) { return Trap; };
+    auto host_foo = [](void*, Instance&, const Value*, int) noexcept { return Trap; };
     const auto host_foo_type = FuncType{{}, {}};
 
     EXPECT_THROW_MESSAGE(instantiate(parse(bin), {{host_foo, nullptr, host_foo_type}}),
diff --git a/test/utils/execute_helpers.hpp b/test/utils/execute_helpers.hpp
index 0a76374c2..04cbb9e4f 100644
--- a/test/utils/execute_helpers.hpp
+++ b/test/utils/execute_helpers.hpp
@@ -11,7 +11,7 @@
 namespace fizzy::test
 {
 inline ExecutionResult execute(const std::unique_ptr<const Module>& module, FuncIdx func_idx,
-    std::initializer_list<Value> args)
+    std::initializer_list<Value> args) noexcept
 {
     auto instance = instantiate(*module);
     return execute(*instance, func_idx, args);
diff --git a/test/utils/fizzy_engine.cpp b/test/utils/fizzy_engine.cpp
index c1a29964d..1b9e8c9cb 100644
--- a/test/utils/fizzy_engine.cpp
+++ b/test/utils/fizzy_engine.cpp
@@ -14,7 +14,7 @@ namespace fizzy::test
 {
 namespace
 {
-fizzy::ExecutionResult env_adler32(void*, Instance& instance, const Value* args, int)
+fizzy::ExecutionResult env_adler32(void*, Instance& instance, const Value* args, int) noexcept
 {
     assert(instance.memory != nullptr);
     const auto ret = fizzy::test::adler32(
diff --git a/tools/wasi/wasi.cpp b/tools/wasi/wasi.cpp
index 04bf56f78..d406f5d46 100644
--- a/tools/wasi/wasi.cpp
+++ b/tools/wasi/wasi.cpp
@@ -18,12 +18,14 @@ namespace
 // and we are a single-run tool. This may change in the future and should reevaluate.
 uvwasi_t state;
 
-fizzy::ExecutionResult wasi_return_enosys(void*, fizzy::Instance&, const fizzy::Value*, int)
+fizzy::ExecutionResult wasi_return_enosys(
+    void*, fizzy::Instance&, const fizzy::Value*, int) noexcept
 {
     return fizzy::Value{uint32_t{UVWASI_ENOSYS}};
 }
 
-fizzy::ExecutionResult wasi_proc_exit(void*, fizzy::Instance&, const fizzy::Value* args, int)
+fizzy::ExecutionResult wasi_proc_exit(
+    void*, fizzy::Instance&, const fizzy::Value* args, int) noexcept
 {
     uvwasi_proc_exit(&state, static_cast<uvwasi_exitcode_t>(args[0].as<uint32_t>()));
     // Should not reach this.
@@ -31,7 +33,7 @@ fizzy::ExecutionResult wasi_proc_exit(void*, fizzy::Instance&, const fizzy::Valu
 }
 
 fizzy::ExecutionResult wasi_fd_write(
-    void*, fizzy::Instance& instance, const fizzy::Value* args, int)
+    void*, fizzy::Instance& instance, const fizzy::Value* args, int) noexcept
 {
     const auto fd = args[0].as<uint32_t>();
     const auto iov_ptr = args[1].as<uint32_t>();
@@ -52,7 +54,8 @@ fizzy::ExecutionResult wasi_fd_write(
     return fizzy::Value{uint32_t{ret}};
 }
 
-fizzy::ExecutionResult wasi_fd_read(void*, fizzy::Instance& instance, const fizzy::Value* args, int)
+fizzy::ExecutionResult wasi_fd_read(
+    void*, fizzy::Instance& instance, const fizzy::Value* args, int) noexcept
 {
     const auto fd = args[0].as<uint32_t>();
     const auto iov_ptr = args[1].as<uint32_t>();
@@ -74,7 +77,7 @@ fizzy::ExecutionResult wasi_fd_read(void*, fizzy::Instance& instance, const fizz
 }
 
 fizzy::ExecutionResult wasi_fd_prestat_get(
-    void*, fizzy::Instance& instance, const fizzy::Value* args, int)
+    void*, fizzy::Instance& instance, const fizzy::Value* args, int) noexcept
 {
     const auto fd = args[0].as<uint32_t>();
     const auto prestat_ptr = args[1].as<uint32_t>();
@@ -88,7 +91,7 @@ fizzy::ExecutionResult wasi_fd_prestat_get(
 }
 
 fizzy::ExecutionResult wasi_environ_sizes_get(
-    void*, fizzy::Instance& instance, const fizzy::Value* args, int)
+    void*, fizzy::Instance& instance, const fizzy::Value* args, int) noexcept
 {
     const auto environc = args[0].as<uint32_t>();
     const auto environ_buf_size = args[1].as<uint32_t>();