diff --git a/.github/actions/setup-php/action.yaml b/.github/actions/setup-php/action.yaml
index 03af29d743..e84e9a198e 100644
--- a/.github/actions/setup-php/action.yaml
+++ b/.github/actions/setup-php/action.yaml
@@ -14,6 +14,10 @@ runs:
         ini-file: development
         # JIT's fixed-address mappings can race Go thread creation during startup.
         ini-values: opcache.jit=disable
+        # libenchant 2.8 can't be loaded again once PHP unloaded it, which each new start of PHP does:
+        # GObject still knows the types of the first load, and aborts when they come back.
+        # To remove once https://github.com/php/php-src/issues/25412 is fixed in the PHP versions tested here
+        extensions: :enchant
         coverage: none
         tools: none
       env:
diff --git a/.github/workflows/sanitizers.yaml b/.github/workflows/sanitizers.yaml
index 0f6e2e2c7c..26cc7034e2 100644
--- a/.github/workflows/sanitizers.yaml
+++ b/.github/workflows/sanitizers.yaml
@@ -31,8 +31,10 @@ jobs:
     env:
       CFLAGS: -g -O0 -fsanitize=${{ matrix.sanitizer == 'asan' && 'address' || 'memory' }} -DZEND_TRACK_ARENA_ALLOC
       LDFLAGS: -fsanitize=${{ matrix.sanitizer == 'asan' && 'address' || 'memory' }}
-      CC: clang
-      CXX: clang++
+      # MemorySanitizer in clang 21, the default of Ubuntu 26.04, takes the index of an AVX-512 permutation
+      # for uninitialized memory: https://github.com/llvm/llvm-project/pull/148785
+      CC: clang-22
+      CXX: clang++-22
       USE_ZEND_ALLOC: 0
       LIBRARY_PATH: ${{ github.workspace }}/php/target/lib:${{ github.workspace }}/watcher/target/lib
       LD_LIBRARY_PATH: ${{ github.workspace }}/php/target/lib
@@ -41,6 +43,8 @@ jobs:
     steps:
       - name: Remove local PHP
         run: sudo apt-get remove --purge --autoremove 'php*' 'libmemcached*'
+      - name: Install clang
+        run: sudo apt-get update && sudo apt-get install -y "${CC}"
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           persist-credentials: false
@@ -56,7 +60,7 @@ jobs:
         uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:
           path: php/target
-          key: php-sanitizers-${{ matrix.sanitizer }}-${{ runner.arch }}-${{ steps.determine-php-version.outputs.version }}
+          key: php-sanitizers-${{ matrix.sanitizer }}-${{ runner.arch }}-${{ steps.determine-php-version.outputs.version }}-${{ hashFiles('.github/workflows/sanitizers.yaml') }}
       - if: steps.cache-php.outputs.cache-hit != 'true'
         name: Compile PHP
         run: |
diff --git a/docs/extensions.md b/docs/extensions.md
index fdb9a5ff45..748561cae0 100644
--- a/docs/extensions.md
+++ b/docs/extensions.md
@@ -671,6 +671,7 @@ In your module, you need to define a new native function that will be called fro
 // extension.go
 package example
 
+// #cgo linux CFLAGS: -D_GNU_SOURCE
 // #include "extension.h"
 import "C"
 import (
@@ -694,6 +695,8 @@ func go_print_something() {
 
 The `frankenphp.RegisterExtension()` function simplifies the extension registration process by handling the internal PHP registration logic. The `go_print_something` function uses the `//export` directive to indicate that it will be accessible in the C code we will write, thanks to CGO.
 
+The `#cgo` line is needed on Linux: CGO includes system headers before `php.h`, and without `_GNU_SOURCE` they don't declare all the functions the PHP headers call, which recent compilers refuse.
+
 In this example, our new function will trigger a goroutine that logs a message in Caddy's logs.
 
 #### Define the PHP function
diff --git a/internal/extgen/cfile_phpmethod_test.go b/internal/extgen/cfile_phpmethod_test.go
index 98e98b3812..345cbee091 100644
--- a/internal/extgen/cfile_phpmethod_test.go
+++ b/internal/extgen/cfile_phpmethod_test.go
@@ -302,6 +302,19 @@ func TestCFile_ClassMethodParamCastsByParamType(t *testing.T) {
 				"(long)name",
 			},
 		},
+		{
+			name:       "int return with nullable params points to values of the types cgo declares",
+			returnType: phpInt,
+			params: []phpParameter{
+				{Name: "name", PhpType: phpString, IsNullable: true},
+				{Name: "count", PhpType: phpInt, IsNullable: true},
+				{Name: "ratio", PhpType: phpFloat, IsNullable: true},
+				{Name: "enabled", PhpType: phpBool, IsNullable: true},
+			},
+			wantContain: []string{
+				"getVarInt_wrapper(intern->go_handle, name_is_null ? NULL : name, count_is_null ? NULL : &(GoInt64){count}, ratio_is_null ? NULL : &ratio, enabled_is_null ? NULL : &(GoUint8){enabled});",
+			},
+		},
 	}
 
 	for _, tt := range tests {
diff --git a/internal/extgen/gofile_test.go b/internal/extgen/gofile_test.go
index 196ca4214f..dbf358b2bb 100644
--- a/internal/extgen/gofile_test.go
+++ b/internal/extgen/gofile_test.go
@@ -1219,6 +1219,7 @@ func (cs *CallableStruct) ProcessOptionalCallback(callback *C.zval) string {
 func testGeneratedFileBasicStructure(t *testing.T, content, expectedPackage, baseName string) {
 	requiredElements := []string{
 		"package " + expectedPackage,
+		"// #cgo linux CFLAGS: -D_GNU_SOURCE",
 		"// #include <stdlib.h>",
 		`// #include "` + baseName + `.h"`,
 		`import "C"`,
diff --git a/internal/extgen/integration_test.go b/internal/extgen/integration_test.go
index a90ab15bea..4ce6fc4daf 100644
--- a/internal/extgen/integration_test.go
+++ b/internal/extgen/integration_test.go
@@ -303,7 +303,7 @@ func TestBasicFunction(t *testing.T) {
 	require.NoError(t, err, "FrankenPHP compilation should succeed")
 
 	err = suite.verifyPHPSymbols(
-		[]string{"test_uppercase", "test_add_numbers", "test_multiply", "test_is_enabled"},
+		[]string{"test_uppercase", "test_add_numbers", "test_multiply", "test_is_enabled", "test_nullables"},
 		[]string{},
 		[]string{},
 	)
@@ -340,6 +340,24 @@ if ($result !== true) {
 	exit(1);
 }
 
+$result = test_nullables(null, null, null);
+if ($result !== "null null null") {
+	echo "FAIL: test_nullables(null, null, null) expected 'null null null', got '$result'";
+	exit(1);
+}
+
+$result = test_nullables(-42, 1.5, true);
+if ($result !== "-42 1.5 true") {
+	echo "FAIL: test_nullables(-42, 1.5, true) expected '-42 1.5 true', got '$result'";
+	exit(1);
+}
+
+$result = test_nullables(0, 0.0, false);
+if ($result !== "0 0 false") {
+	echo "FAIL: test_nullables(0, 0.0, false) expected '0 0 false', got '$result'";
+	exit(1);
+}
+
 echo "OK";
 `, "OK")
 	require.NoError(t, err, "all function calls should work correctly")
@@ -416,6 +434,25 @@ if ($counter->getValue() !== 50) {
 	exit(1);
 }
 
+$counter->resetIf(null);
+if ($counter->getValue() !== 50) {
+	echo "FAIL: Counter after resetIf(null) expected 50 (unchanged), got " . $counter->getValue();
+	exit(1);
+}
+
+$counter->resetIf(false);
+if ($counter->getValue() !== 50) {
+	echo "FAIL: Counter after resetIf(false) expected 50 (unchanged), got " . $counter->getValue();
+	exit(1);
+}
+
+$counter->resetIf(true);
+if ($counter->getValue() !== 0) {
+	echo "FAIL: Counter after resetIf(true) expected 0, got " . $counter->getValue();
+	exit(1);
+}
+
+$counter->setValue(50);
 $counter->reset();
 if ($counter->getValue() !== 0) {
 	echo "FAIL: Counter after reset expected 0, got " . $counter->getValue();
diff --git a/internal/extgen/paramparser.go b/internal/extgen/paramparser.go
index a9f40c3054..66f6d51249 100644
--- a/internal/extgen/paramparser.go
+++ b/internal/extgen/paramparser.go
@@ -168,12 +168,14 @@ func (pp *ParameterParser) generateSingleGoCallParam(param phpParameter) string
 		switch param.PhpType {
 		case phpString:
 			return fmt.Sprintf("%s_is_null ? NULL : %s", param.Name, param.Name)
+		// cgo declares *int64 and *bool as GoInt64 * and GoUint8 *, which GCC 14+
+		// refuses to mix with zend_long * and zend_bool *: point to a copy of the right type
 		case phpInt:
-			return fmt.Sprintf("%s_is_null ? NULL : &%s", param.Name, param.Name)
+			return fmt.Sprintf("%s_is_null ? NULL : &(GoInt64){%s}", param.Name, param.Name)
 		case phpFloat:
 			return fmt.Sprintf("%s_is_null ? NULL : &%s", param.Name, param.Name)
 		case phpBool:
-			return fmt.Sprintf("%s_is_null ? NULL : &%s", param.Name, param.Name)
+			return fmt.Sprintf("%s_is_null ? NULL : &(GoUint8){%s}", param.Name, param.Name)
 		case phpCallable:
 			return fmt.Sprintf("%s_callback", param.Name)
 		default:
diff --git a/internal/extgen/paramparser_test.go b/internal/extgen/paramparser_test.go
index c53a55874d..c59e77d023 100644
--- a/internal/extgen/paramparser_test.go
+++ b/internal/extgen/paramparser_test.go
@@ -503,7 +503,7 @@ func TestParameterParser_GenerateSingleGoCallParam(t *testing.T) {
 		{
 			name:     "nullable int parameter",
 			param:    phpParameter{Name: "count", PhpType: phpInt, IsNullable: true},
-			expected: "count_is_null ? NULL : &count",
+			expected: "count_is_null ? NULL : &(GoInt64){count}",
 		},
 		{
 			name:     "float parameter",
@@ -523,7 +523,7 @@ func TestParameterParser_GenerateSingleGoCallParam(t *testing.T) {
 		{
 			name:     "nullable bool parameter",
 			param:    phpParameter{Name: "enabled", PhpType: phpBool, IsNullable: true},
-			expected: "enabled_is_null ? NULL : &enabled",
+			expected: "enabled_is_null ? NULL : &(GoUint8){enabled}",
 		},
 		{
 			name:     "array parameter",
diff --git a/internal/extgen/templates/extension.c.tpl b/internal/extgen/templates/extension.c.tpl
index 9a03bace2e..545948e5c9 100644
--- a/internal/extgen/templates/extension.c.tpl
+++ b/internal/extgen/templates/extension.c.tpl
@@ -9,7 +9,7 @@
 
 {{define "methodCallArg" -}}
 {{- if .IsNullable -}}
-{{if eq .PhpType "string"}}{{.Name}}_is_null ? NULL : {{.Name}}{{else if eq .PhpType "int"}}{{.Name}}_is_null ? NULL : &{{.Name}}{{else if eq .PhpType "float"}}{{.Name}}_is_null ? NULL : &{{.Name}}{{else if eq .PhpType "bool"}}{{.Name}}_is_null ? NULL : &{{.Name}}{{else if eq .PhpType "array"}}{{.Name}}{{else if eq .PhpType "mixed"}}{{.Name}}{{else if eq .PhpType "callable"}}{{.Name}}_callback{{end}}
+{{if eq .PhpType "string"}}{{.Name}}_is_null ? NULL : {{.Name}}{{else if eq .PhpType "int"}}{{.Name}}_is_null ? NULL : &(GoInt64){ {{- .Name -}} }{{else if eq .PhpType "float"}}{{.Name}}_is_null ? NULL : &{{.Name}}{{else if eq .PhpType "bool"}}{{.Name}}_is_null ? NULL : &(GoUint8){ {{- .Name -}} }{{else if eq .PhpType "array"}}{{.Name}}{{else if eq .PhpType "mixed"}}{{.Name}}{{else if eq .PhpType "callable"}}{{.Name}}_callback{{end}}
 {{- else -}}
 {{if eq .PhpType "string"}}{{.Name}}{{else if eq .PhpType "int"}}(long){{.Name}}{{else if eq .PhpType "float"}}(double){{.Name}}{{else if eq .PhpType "bool"}}(int){{.Name}}{{else if eq .PhpType "array"}}{{.Name}}{{else if eq .PhpType "mixed"}}{{.Name}}{{else if eq .PhpType "callable"}}{{.Name}}_callback{{end}}
 {{- end -}}
diff --git a/internal/extgen/templates/extension.go.tpl b/internal/extgen/templates/extension.go.tpl
index d5d8889fc8..9088315a88 100644
--- a/internal/extgen/templates/extension.go.tpl
+++ b/internal/extgen/templates/extension.go.tpl
@@ -9,6 +9,7 @@ package {{.PackageName}}
 // You may edit the file and remove this comment if you plan to manually maintain
 // this file going forward.
 
+// #cgo linux CFLAGS: -D_GNU_SOURCE
 // #include <stdlib.h>
 // #include "{{.BaseName}}.h"
 import "C"
diff --git a/testdata/integration/basic_function.go b/testdata/integration/basic_function.go
index 5004764602..39669d45e6 100644
--- a/testdata/integration/basic_function.go
+++ b/testdata/integration/basic_function.go
@@ -3,6 +3,7 @@ package testintegration
 // #include <Zend/zend_types.h>
 import "C"
 import (
+	"strconv"
 	"strings"
 	"unsafe"
 
@@ -30,3 +31,19 @@ func test_multiply(a float64, b float64) float64 {
 func test_is_enabled(flag bool) bool {
 	return !flag
 }
+
+// export_php:function test_nullables(?int $count, ?float $ratio, ?bool $flag): string
+func test_nullables(count *int64, ratio *float64, flag *bool) unsafe.Pointer {
+	values := []string{"null", "null", "null"}
+	if count != nil {
+		values[0] = strconv.FormatInt(*count, 10)
+	}
+	if ratio != nil {
+		values[1] = strconv.FormatFloat(*ratio, 'f', -1, 64)
+	}
+	if flag != nil {
+		values[2] = strconv.FormatBool(*flag)
+	}
+
+	return frankenphp.PHPString(strings.Join(values, " "), false)
+}
diff --git a/testdata/integration/class_methods.go b/testdata/integration/class_methods.go
index e84d346a15..7169799871 100644
--- a/testdata/integration/class_methods.go
+++ b/testdata/integration/class_methods.go
@@ -51,6 +51,13 @@ func (c *CounterStruct) UpdateWithNullable(newValue *int64) {
 	}
 }
 
+// export_php:method Counter::resetIf(?bool $condition): void
+func (c *CounterStruct) ResetIf(condition *bool) {
+	if condition != nil && *condition {
+		c.Value = 0
+	}
+}
+
 // export_php:class StringHolder
 type StringHolderStruct struct {
 	Data string