diff --git a/libc/bionic/heap_tagging.cpp b/libc/bionic/heap_tagging.cpp
index 49b02da..9805fbd 100644
--- a/libc/bionic/heap_tagging.cpp
+++ b/libc/bionic/heap_tagging.cpp
@@ -96,12 +96,7 @@
 }
 
 // Requires `g_heap_tagging_lock` to be held.
-bool SetHeapTaggingLevel(void* arg, size_t arg_size) {
-  if (arg_size != sizeof(HeapTaggingLevel)) {
-    return false;
-  }
-
-  auto tag_level = *reinterpret_cast<HeapTaggingLevel*>(arg);
+bool SetHeapTaggingLevel(HeapTaggingLevel tag_level) {
   if (tag_level == heap_tagging_level) {
     return true;
   }
diff --git a/libc/bionic/heap_tagging.h b/libc/bionic/heap_tagging.h
index db45fc1..110b6ed 100644
--- a/libc/bionic/heap_tagging.h
+++ b/libc/bionic/heap_tagging.h
@@ -42,5 +42,5 @@
 
 // These functions can be called in a multithreaded context, and thus should
 // only be called when holding the `g_heap_tagging_lock`.
-bool SetHeapTaggingLevel(void* arg, size_t arg_size);
+bool SetHeapTaggingLevel(HeapTaggingLevel level);
 HeapTaggingLevel GetHeapTaggingLevel();
diff --git a/libc/bionic/malloc_common.cpp b/libc/bionic/malloc_common.cpp
index 0ee12a7..955cf18 100644
--- a/libc/bionic/malloc_common.cpp
+++ b/libc/bionic/malloc_common.cpp
@@ -102,6 +102,15 @@
 }
 
 extern "C" int mallopt(int param, int value) {
+  // Some are handled by libc directly rather than by the allocator.
+  if (param == M_BIONIC_SET_HEAP_TAGGING_LEVEL) {
+    ScopedPthreadMutexLocker locker(&g_heap_tagging_lock);
+    return SetHeapTaggingLevel(static_cast<HeapTaggingLevel>(value));
+  }
+  if (param == M_BIONIC_DISABLE_MEMORY_MITIGATIONS) {
+    return DisableMemoryMitigations(value);
+  }
+  // The rest we pass on...
   auto dispatch_table = GetDispatchTable();
   if (__predict_false(dispatch_table != nullptr)) {
     return dispatch_table->mallopt(param, value);
@@ -316,9 +325,8 @@
   if (opcode == M_SET_ALLOCATION_LIMIT_BYTES) {
     return LimitEnable(arg, arg_size);
   }
-  if (opcode == M_SET_HEAP_TAGGING_LEVEL) {
-    ScopedPthreadMutexLocker locker(&g_heap_tagging_lock);
-    return SetHeapTaggingLevel(arg, arg_size);
+  if (opcode == M_SET_HEAP_TAGGING_LEVEL && arg_size == sizeof(HeapTaggingLevel)) {
+    return mallopt(M_BIONIC_SET_HEAP_TAGGING_LEVEL, *reinterpret_cast<HeapTaggingLevel*>(arg));
   }
   if (opcode == M_INITIALIZE_GWP_ASAN) {
     if (arg == nullptr || arg_size != sizeof(bool)) {
@@ -329,8 +337,8 @@
       return MaybeInitGwpAsan(globals, *reinterpret_cast<bool*>(arg));
     });
   }
-  if (opcode == M_DISABLE_MEMORY_MITIGATIONS) {
-    return DisableMemoryMitigations(arg, arg_size);
+  if (opcode == M_DISABLE_MEMORY_MITIGATIONS && arg_size == sizeof(int)) {
+    return mallopt(M_BIONIC_DISABLE_MEMORY_MITIGATIONS, reinterpret_cast<intptr_t>(arg));
   }
   errno = ENOTSUP;
   return false;
diff --git a/libc/bionic/malloc_common_dynamic.cpp b/libc/bionic/malloc_common_dynamic.cpp
index 2d6a1bb..93d4d53 100644
--- a/libc/bionic/malloc_common_dynamic.cpp
+++ b/libc/bionic/malloc_common_dynamic.cpp
@@ -523,9 +523,8 @@
     }
     return FreeMallocLeakInfo(reinterpret_cast<android_mallopt_leak_info_t*>(arg));
   }
-  if (opcode == M_SET_HEAP_TAGGING_LEVEL) {
-    ScopedPthreadMutexLocker locker(&g_heap_tagging_lock);
-    return SetHeapTaggingLevel(arg, arg_size);
+  if (opcode == M_SET_HEAP_TAGGING_LEVEL && arg_size == sizeof(HeapTaggingLevel)) {
+    return mallopt(M_BIONIC_SET_HEAP_TAGGING_LEVEL, *reinterpret_cast<HeapTaggingLevel*>(arg));
   }
   if (opcode == M_INITIALIZE_GWP_ASAN) {
     if (arg == nullptr || arg_size != sizeof(bool)) {
@@ -536,8 +535,8 @@
       return MaybeInitGwpAsan(globals, *reinterpret_cast<bool*>(arg));
     });
   }
-  if (opcode == M_DISABLE_MEMORY_MITIGATIONS) {
-    return DisableMemoryMitigations(arg, arg_size);
+  if (opcode == M_DISABLE_MEMORY_MITIGATIONS && arg_size == sizeof(int)) {
+    return mallopt(M_BIONIC_DISABLE_MEMORY_MITIGATIONS, reinterpret_cast<intptr_t>(arg));
   }
   // Try heapprofd's mallopt, as it handles options not covered here.
   return HeapprofdMallopt(opcode, arg, arg_size);
diff --git a/libc/bionic/memory_mitigation_state.cpp b/libc/bionic/memory_mitigation_state.cpp
index 4761d88..b262f86 100644
--- a/libc/bionic/memory_mitigation_state.cpp
+++ b/libc/bionic/memory_mitigation_state.cpp
@@ -47,8 +47,8 @@
 
 extern "C" void scudo_malloc_set_zero_contents(int zero_contents);
 
-bool DisableMemoryMitigations(void* arg, size_t arg_size) {
-  if (arg || arg_size) {
+bool DisableMemoryMitigations(int arg) {
+  if (arg != 0) {
     return false;
   }
 
@@ -61,7 +61,7 @@
   HeapTaggingLevel current_level = GetHeapTaggingLevel();
   if (current_level != M_HEAP_TAGGING_LEVEL_NONE && current_level != M_HEAP_TAGGING_LEVEL_TBI) {
     HeapTaggingLevel level = M_HEAP_TAGGING_LEVEL_NONE;
-    SetHeapTaggingLevel(reinterpret_cast<void*>(&level), sizeof(level));
+    SetHeapTaggingLevel(level);
   }
 
   return true;
diff --git a/libc/bionic/memory_mitigation_state.h b/libc/bionic/memory_mitigation_state.h
index ffa1912..047b6ad 100644
--- a/libc/bionic/memory_mitigation_state.h
+++ b/libc/bionic/memory_mitigation_state.h
@@ -30,4 +30,4 @@
 
 #include <stddef.h>
 
-bool DisableMemoryMitigations(void* arg, size_t arg_size);
+bool DisableMemoryMitigations(int arg);