diff --git a/atom/src/behaviors.h b/atom/src/behaviors.h
index 5c82ec83..3e98bad2 100644
--- a/atom/src/behaviors.h
+++ b/atom/src/behaviors.h
@@ -205,8 +205,28 @@ enum Mode: uint8_t
     Property,
     ObjectMethod_Name,
     MemberMethod_Object,
+    Last // sentinel
 };
 
 }  // namespace GetState
 
+constexpr uint8_t _required_handler_size(uint8_t x) {
+    return (
+        (x > 128) ? 255 :
+        (x > 64) ? 128 :
+        (x > 32) ? 64 :
+        (x > 16) ? 32 :
+        (x > 8) ? 16 :
+        (x > 4) ? 8 :
+        (x > 2) ? 4 :
+        2
+    );
+}
+
+#define _handlers_size( a ) ( sizeof(a) / sizeof(a[0]) )
+#define validate_handlers( handlers, sentinel ) \
+    _handlers_size(handlers) - 1; \
+    static_assert(sentinel <= _handlers_size(handlers), "Not enough handlers for all enum values"); \
+    static_assert(_required_handler_size(sentinel) == _handlers_size(handlers), "Handlers size does not match enum width") \
+
 }  // namespace atom
diff --git a/atom/src/defaultvaluebehavior.cpp b/atom/src/defaultvaluebehavior.cpp
index 3e547c48..e8b5a579 100644
--- a/atom/src/defaultvaluebehavior.cpp
+++ b/atom/src/defaultvaluebehavior.cpp
@@ -207,7 +207,7 @@ handlers[] = {
     no_op_handler
 };
 
-static_assert( sizeof(handlers) / sizeof(handler) == 16, "Must be exactly 16 handlers" );
+const auto mask = validate_handlers(handlers, DefaultValue::Mode::Last);
 
 }  // namespace
 
@@ -215,7 +215,7 @@ static_assert( sizeof(handlers) / sizeof(handler) == 16, "Must be exactly 16 han
 PyObject*
 Member::default_value( CAtom* atom )
 {
-    return handlers[ get_default_value_mode() & 0xf ]( this, atom );
+    return handlers[ get_default_value_mode() & mask ]( this, atom );
 }
 
 
diff --git a/atom/src/delattrbehavior.cpp b/atom/src/delattrbehavior.cpp
index 651850d6..62091f58 100644
--- a/atom/src/delattrbehavior.cpp
+++ b/atom/src/delattrbehavior.cpp
@@ -192,7 +192,7 @@ handlers[] = {
     property_handler
 };
 
-static_assert( sizeof(handlers) / sizeof(handler) == 8, "Must be exactly 8 handlers" );
+const auto mask = validate_handlers(handlers, DelAttr::Mode::Last);
 
 }  // namespace
 
@@ -200,7 +200,7 @@ static_assert( sizeof(handlers) / sizeof(handler) == 8, "Must be exactly 8 handl
 int
 Member::delattr( CAtom* atom )
 {
-    return handlers[ get_delattr_mode() & 0x7 ]( this, atom );
+    return handlers[ get_delattr_mode() & mask ]( this, atom );
 }
 
 
diff --git a/atom/src/getattrbehavior.cpp b/atom/src/getattrbehavior.cpp
index e54a0205..ae6f40b6 100644
--- a/atom/src/getattrbehavior.cpp
+++ b/atom/src/getattrbehavior.cpp
@@ -263,7 +263,7 @@ handlers[] = {
     no_op_handler
 };
 
-static_assert( sizeof(handlers) / sizeof(handler) == 16, "Must be exactly 16 handlers" );
+const auto mask = validate_handlers(handlers, GetAttr::Mode::Last);
 
 }  // namespace
 
@@ -271,7 +271,7 @@ static_assert( sizeof(handlers) / sizeof(handler) == 16, "Must be exactly 16 han
 PyObject*
 Member::getattr( CAtom* atom )
 {
-    return handlers[ get_getattr_mode() & 0xf ]( this, atom );
+    return handlers[ get_getattr_mode() & mask ]( this, atom );
 }
 
 }  // namespace atom
diff --git a/atom/src/getstatebehavior.cpp b/atom/src/getstatebehavior.cpp
index b7a17e2c..cd06fa19 100644
--- a/atom/src/getstatebehavior.cpp
+++ b/atom/src/getstatebehavior.cpp
@@ -129,7 +129,7 @@ handlers[] = {
     include_handler
 };
 
-static_assert( sizeof(handlers) / sizeof(handler) == 8, "Must be exactly 8 handlers" );
+const auto mask = validate_handlers(handlers, GetState::Mode::Last);
 
 }  // namespace
 
@@ -137,7 +137,7 @@ static_assert( sizeof(handlers) / sizeof(handler) == 8, "Must be exactly 8 handl
 PyObject*
 Member::should_getstate( CAtom* atom )
 {
-    return handlers[ get_getstate_mode() & 0x7 ]( this, atom );
+    return handlers[ get_getstate_mode() & mask ]( this, atom );
 }
 
 }  // namespace atom
diff --git a/atom/src/postgetattrbehavior.cpp b/atom/src/postgetattrbehavior.cpp
index 919a0998..31d2b94a 100644
--- a/atom/src/postgetattrbehavior.cpp
+++ b/atom/src/postgetattrbehavior.cpp
@@ -99,7 +99,7 @@ handlers[] = {
     no_op_handler,
 };
 
-static_assert( sizeof(handlers) / sizeof(handler) == 8, "Must be exactly 8 handlers" );
+const auto mask = validate_handlers(handlers, PostGetAttr::Mode::Last);
 
 }  // namespace
 
@@ -107,7 +107,7 @@ static_assert( sizeof(handlers) / sizeof(handler) == 8, "Must be exactly 8 handl
 PyObject*
 Member::post_getattr( CAtom* atom, PyObject* value )
 {
-    return handlers[ get_post_getattr_mode() & 0x7 ]( this, atom, value );
+    return handlers[ get_post_getattr_mode() & mask ]( this, atom, value );
 }
 
 
diff --git a/atom/src/postsetattrbehavior.cpp b/atom/src/postsetattrbehavior.cpp
index c4af2089..3cbab2a8 100644
--- a/atom/src/postsetattrbehavior.cpp
+++ b/atom/src/postsetattrbehavior.cpp
@@ -112,7 +112,7 @@ handlers[] = {
     no_op_handler
 };
 
-static_assert( sizeof(handlers) / sizeof(handler) == 8, "Must be exactly 8 handlers" );
+const auto mask = validate_handlers(handlers, PostSetAttr::Mode::Last);
 
 }  // namespace
 
@@ -120,7 +120,7 @@ static_assert( sizeof(handlers) / sizeof(handler) == 8, "Must be exactly 8 handl
 int
 Member::post_setattr( CAtom* atom, PyObject* oldvalue, PyObject* newvalue )
 {
-    return handlers[ get_post_setattr_mode() & 0x7 ]( this, atom, oldvalue, newvalue );
+    return handlers[ get_post_setattr_mode() & mask ]( this, atom, oldvalue, newvalue );
 }
 
 
diff --git a/atom/src/postvalidatebehavior.cpp b/atom/src/postvalidatebehavior.cpp
index 4f0527e2..274917a0 100644
--- a/atom/src/postvalidatebehavior.cpp
+++ b/atom/src/postvalidatebehavior.cpp
@@ -103,7 +103,7 @@ handlers[] = {
     no_op_handler
 };
 
-static_assert( sizeof(handlers) / sizeof(handler) == 8, "Must be exactly 8 handlers" );
+const auto mask = validate_handlers(handlers, PostValidate::Mode::Last);
 
 }  // namespace
 
@@ -111,7 +111,7 @@ static_assert( sizeof(handlers) / sizeof(handler) == 8, "Must be exactly 8 handl
 PyObject*
 Member::post_validate( CAtom* atom, PyObject* oldvalue, PyObject* newvalue )
 {
-    return handlers[ get_post_validate_mode() & 0x7 ]( this, atom, oldvalue, newvalue );
+    return handlers[ get_post_validate_mode() & mask ]( this, atom, oldvalue, newvalue );
 }
 
 }  // namespace atom
diff --git a/atom/src/setattrbehavior.cpp b/atom/src/setattrbehavior.cpp
index 0497cf16..dda99b25 100644
--- a/atom/src/setattrbehavior.cpp
+++ b/atom/src/setattrbehavior.cpp
@@ -383,7 +383,7 @@ handlers[] = {
     no_op_handler
 };
 
-static_assert( sizeof(handlers) / sizeof(handler) == 16, "Must be exactly 16 handlers" );
+const auto mask = validate_handlers(handlers, SetAttr::Mode::Last);
 
 } // namespace
 
@@ -391,7 +391,7 @@ static_assert( sizeof(handlers) / sizeof(handler) == 16, "Must be exactly 16 han
 int
 Member::setattr( CAtom* atom, PyObject* value )
 {
-    return handlers[ get_setattr_mode() & 0xf ]( this, atom, value );
+    return handlers[ get_setattr_mode() & mask ]( this, atom, value );
 }
 
 
diff --git a/atom/src/validatebehavior.cpp b/atom/src/validatebehavior.cpp
index 4746f5dd..ea27b818 100644
--- a/atom/src/validatebehavior.cpp
+++ b/atom/src/validatebehavior.cpp
@@ -1000,6 +1000,7 @@ handlers[] = {
     member_method_object_old_new_handler
 };
 
+const auto mask = validate_handlers(handlers, Validate::Mode::Last);
 
 }  // namespace
 
@@ -1007,9 +1008,7 @@ handlers[] = {
 PyObject*
 Member::validate( CAtom* atom, PyObject* oldvalue, PyObject* newvalue )
 {
-    if( get_validate_mode() >= sizeof( handlers ) / sizeof( handler ) )
-        return no_op_handler( this, atom, oldvalue, newvalue );  // LCOV_EXCL_LINE
-    return handlers[ get_validate_mode() ]( this, atom, oldvalue, newvalue );
+    return handlers[ get_validate_mode() & mask ]( this, atom, oldvalue, newvalue );
 }