diff --git a/py/map.h b/py/map.h
index ce5505571c..afebfda6ec 100644
--- a/py/map.h
+++ b/py/map.h
@@ -4,11 +4,9 @@ typedef struct _mp_map_elem_t {
 } mp_map_elem_t;
 
 typedef struct _mp_map_t {
-    struct {
-        machine_uint_t all_keys_are_qstrs : 1;
-        machine_uint_t table_is_fixed_array : 1;
-        machine_uint_t used : (8 * sizeof(machine_uint_t) - 2);
-    };
+    machine_uint_t all_keys_are_qstrs : 1;
+    machine_uint_t table_is_fixed_array : 1;
+    machine_uint_t used : (8 * sizeof(machine_uint_t) - 2);
     machine_uint_t alloc;
     mp_map_elem_t *table;
 } mp_map_t;
diff --git a/py/misc.h b/py/misc.h
index 278d59d4fa..3671f42d87 100644
--- a/py/misc.h
+++ b/py/misc.h
@@ -66,10 +66,8 @@ typedef struct _vstr_t {
     int alloc;
     int len;
     char *buf;
-    struct {
-        bool had_error : 1;
-        bool fixed_buf : 1;
-    };
+    bool had_error : 1;
+    bool fixed_buf : 1;
 } vstr_t;
 
 // convenience macro to declare a vstr with a fixed size buffer on the stack
diff --git a/py/mpz.h b/py/mpz.h
index 4a0eba1c12..13a96fd797 100644
--- a/py/mpz.h
+++ b/py/mpz.h
@@ -3,10 +3,8 @@ typedef uint32_t mpz_dbl_dig_t;
 typedef int32_t mpz_dbl_dig_signed_t;
 
 typedef struct _mpz_t {
-    struct {
-        machine_uint_t neg : 1;
-        machine_uint_t alloc : 31;
-    };
+    machine_uint_t neg : 1;
+    machine_uint_t alloc : 31;
     machine_uint_t len;
     mpz_dig_t *dig;
 } mpz_t;
diff --git a/py/obj.h b/py/obj.h
index c21c859596..b664b09443 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -54,7 +54,7 @@ typedef struct _mp_obj_base_t mp_obj_base_t;
 
 #define MP_DECLARE_CONST_FUN_OBJ(obj_name) extern const mp_obj_fun_native_t obj_name
 
-#define MP_DEFINE_CONST_FUN_OBJ_VOID_PTR(obj_name, is_kw, n_args_min, n_args_max, fun_name) const mp_obj_fun_native_t obj_name = {{&fun_native_type}, {is_kw, n_args_min}, n_args_max, (void *)fun_name}
+#define MP_DEFINE_CONST_FUN_OBJ_VOID_PTR(obj_name, is_kw, n_args_min, n_args_max, fun_name) const mp_obj_fun_native_t obj_name = {{&fun_native_type}, is_kw, n_args_min, n_args_max, (void *)fun_name}
 #define MP_DEFINE_CONST_FUN_OBJ_0(obj_name, fun_name) MP_DEFINE_CONST_FUN_OBJ_VOID_PTR(obj_name, false, 0, 0, (mp_fun_0_t)fun_name)
 #define MP_DEFINE_CONST_FUN_OBJ_1(obj_name, fun_name) MP_DEFINE_CONST_FUN_OBJ_VOID_PTR(obj_name, false, 1, 1, (mp_fun_1_t)fun_name)
 #define MP_DEFINE_CONST_FUN_OBJ_2(obj_name, fun_name) MP_DEFINE_CONST_FUN_OBJ_VOID_PTR(obj_name, false, 2, 2, (mp_fun_2_t)fun_name)
@@ -374,10 +374,8 @@ mp_obj_t mp_obj_new_bytearray_by_ref(uint n, void *items);
 // functions
 typedef struct _mp_obj_fun_native_t { // need this so we can define const objects (to go in ROM)
     mp_obj_base_t base;
-    struct {
-        bool is_kw : 1;
-        machine_uint_t n_args_min : (8 * sizeof(machine_uint_t) - 1); // inclusive
-    };
+    bool is_kw : 1;
+    machine_uint_t n_args_min : (8 * sizeof(machine_uint_t) - 1); // inclusive
     machine_uint_t n_args_max; // inclusive
     void *fun;
     // TODO add mp_map_t *globals
diff --git a/py/objarray.c b/py/objarray.c
index 9e36196e5b..30a2183115 100644
--- a/py/objarray.c
+++ b/py/objarray.c
@@ -16,12 +16,10 @@
 
 typedef struct _mp_obj_array_t {
     mp_obj_base_t base;
-    struct {
-        machine_uint_t typecode : 8;
-        // free is number of unused elements after len used elements
-        // alloc size = len + free
-        machine_uint_t free : (8 * sizeof(machine_uint_t) - 8);
-    };
+    machine_uint_t typecode : 8;
+    // free is number of unused elements after len used elements
+    // alloc size = len + free
+    machine_uint_t free : (8 * sizeof(machine_uint_t) - 8);
     machine_uint_t len; // in elements
     void *items;
 } mp_obj_array_t;
diff --git a/py/objfun.c b/py/objfun.c
index 7c89c47000..6cdc97cc6d 100644
--- a/py/objfun.c
+++ b/py/objfun.c
@@ -143,12 +143,10 @@ mp_obj_t rt_make_function_var_between(int n_args_min, int n_args_max, mp_fun_var
 typedef struct _mp_obj_fun_bc_t {
     mp_obj_base_t base;
     mp_map_t *globals;      // the context within which this function was defined
-    struct {
-        machine_uint_t n_args : 15;         // number of arguments this function takes
-        machine_uint_t n_def_args : 15;     // number of default arguments
-        machine_uint_t takes_var_args : 1;  // set if this function takes variable args
-        machine_uint_t takes_kw_args : 1;   // set if this function takes keyword args
-    };
+    machine_uint_t n_args : 15;         // number of arguments this function takes
+    machine_uint_t n_def_args : 15;     // number of default arguments
+    machine_uint_t takes_var_args : 1;  // set if this function takes variable args
+    machine_uint_t takes_kw_args : 1;   // set if this function takes keyword args
     uint n_state;           // total state size for the executing function (incl args, locals, stack)
     const byte *bytecode;   // bytecode for the function
     qstr *args;             // argument names (needed to resolve positional args passed as keywords)
diff --git a/py/runtime.c b/py/runtime.c
index 20bfa0b20f..b9caf04570 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -45,14 +45,10 @@ typedef enum {
 } mp_code_kind_t;
 
 typedef struct _mp_code_t {
-    struct {
-        mp_code_kind_t kind : 8;
-        uint scope_flags : 8;
-    };
-    struct {
-        uint n_args : 16;
-        uint n_state : 16;
-    };
+    mp_code_kind_t kind : 8;
+    uint scope_flags : 8;
+    uint n_args : 16;
+    uint n_state : 16;
     union {
         struct {
             byte *code;