diff --git a/CMakeLists.txt b/CMakeLists.txt
index ea560ead..47843097 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -166,7 +166,10 @@ endif()
 
 # Compiler flags
 if(CMAKE_C_COMPILER_ID MATCHES "AppleClang|Clang|GNU")
-  list(APPEND mi_cflags -Wall -Wextra -Wno-unknown-pragmas -Wstrict-prototypes -fvisibility=hidden)
+  list(APPEND mi_cflags -Wall -Wextra -Wno-unknown-pragmas -fvisibility=hidden)
+  if(NOT MI_USE_CXX)
+    list(APPEND mi_cflags -Wstrict-prototypes)
+  endif()
   if(CMAKE_C_COMPILER_ID MATCHES "GNU")
     list(APPEND mi_cflags -Wno-invalid-memory-model)
   endif()
diff --git a/src/alloc-override-osx.c b/src/alloc-override-osx.c
index a2e341bb..723ef226 100644
--- a/src/alloc-override-osx.c
+++ b/src/alloc-override-osx.c
@@ -189,6 +189,10 @@ static malloc_zone_t* mi_get_default_zone()
   }
 }
 
+#if defined(__GNUC__) && !defined(__clang__)
+#pragma GCC diagnostic ignored "-Wmissing-field-initializers"
+#endif
+
 static malloc_introspection_t mi_introspect = {
   .enumerator = &intro_enumerator,
   .good_size = &intro_good_size,
@@ -199,23 +203,23 @@ static malloc_introspection_t mi_introspect = {
   .force_unlock = &intro_force_unlock,
 #if defined(MAC_OS_X_VERSION_10_6) && \
     MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_6
-  .zone_locked = &intro_zone_locked,
   .statistics = &intro_statistics,
+  .zone_locked = &intro_zone_locked,
 #endif
 };
 
 static malloc_zone_t mi_malloc_zone = {
   .size = &zone_size,
-  .zone_name = "mimalloc",
-  .introspect = &mi_introspect,
   .malloc = &zone_malloc,
   .calloc = &zone_calloc,
   .valloc = &zone_valloc,
   .free = &zone_free,
   .realloc = &zone_realloc,
   .destroy = &zone_destroy,
+  .zone_name = "mimalloc",
   .batch_malloc = &zone_batch_malloc,
   .batch_free = &zone_batch_free,
+  .introspect = &mi_introspect,  
 #if defined(MAC_OS_X_VERSION_10_6) && \
     MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_6
   // switch to version 9 on OSX 10.6 to support memalign.
@@ -243,16 +247,22 @@ __attribute__((used)) static struct {
 };
 #endif
 
-static void __attribute__((constructor(0))) _mi_macos_override_malloc() {
+
+#if defined(__clang__)
+__attribute__((constructor(0))) 
+#else
+__attribute__((constructor))      // seems not supported by g++-11 on the M1
+#endif
+static void _mi_macos_override_malloc() {
   malloc_zone_t* purgeable_zone = NULL;
 
-#if defined(MAC_OS_X_VERSION_10_6) && \
+  #if defined(MAC_OS_X_VERSION_10_6) && \
     MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_6
   // force the purgeable zone to exist to avoid strange bugs
   if (malloc_default_purgeable_zone) {
     purgeable_zone = malloc_default_purgeable_zone();
   }
-#endif
+  #endif
 
   // Register our zone.
   // thomcc: I think this is still needed to put us in the zone list.
diff --git a/src/arena.c b/src/arena.c
index ccf64ba1..3072dbae 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -324,7 +324,7 @@ bool mi_manage_os_memory(void* start, size_t size, bool is_committed, bool is_la
   // the bitmaps are already zero initialized due to os_alloc
   // initialize committed bitmap?
   if (arena->blocks_committed != NULL && is_committed) {
-    memset(arena->blocks_committed, 0xFF, fields*sizeof(mi_bitmap_field_t));
+    memset((void*)arena->blocks_committed, 0xFF, fields*sizeof(mi_bitmap_field_t)); // cast to void* to avoid atomic warning
   }
   // and claim leftover blocks if needed (so we never allocate there)
   ptrdiff_t post = (fields * MI_BITMAP_FIELD_BITS) - bcount;