diff --git a/releasenotes.md b/releasenotes.md
index f617b0008..2c331618d 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -17,6 +17,7 @@
 - Correctly silence "unsupported architecture" warning with `--quiet` #2465
 - Overloading &[] should be enough for foreach. #2466
 - Any register allowed in X86_64 inline asm address. #2463
+- int val = some_int + some_distinct_inline_int errors that int cannot be cast to DistinctInt #2468
 
 ### Stdlib changes
 - Added generic `InterfaceList` to store a list of values that implement a specific interface
diff --git a/src/compiler/compiler_internal.h b/src/compiler/compiler_internal.h
index 8d69ad13f..278ae64dc 100644
--- a/src/compiler/compiler_internal.h
+++ b/src/compiler/compiler_internal.h
@@ -2541,7 +2541,7 @@ AlignSize type_abi_alignment(Type *type);
 bool type_func_match(Type *fn_type, Type *rtype, unsigned arg_count, ...);
 AlignSize type_alloca_alignment(Type *type);
 Type *type_find_largest_union_element(Type *type);
-Type *type_find_max_type(Type *type, Type *other);
+Type *type_find_max_type(Type *type, Type *other, Expr *first, Expr *second);
 Type *type_find_max_type_may_fail(Type *type, Type *other);
 Type *type_abi_find_single_struct_element(Type *type);
 Module *type_base_module(Type *type);
@@ -3118,16 +3118,32 @@ static inline Type *type_base(Type *type)
 	}
 }
 
+
+static const bool is_distinct_like[TYPE_LAST + 1] = {
+	[TYPE_ENUM] = true,
+	[TYPE_CONST_ENUM] = true,
+	[TYPE_DISTINCT] = true
+};
+
+INLINE bool typekind_is_distinct_like(TypeKind kind)
+{
+	return is_distinct_like[kind];
+}
+
 INLINE bool type_is_distinct_like(Type *type)
 {
-	TypeKind kind = type->type_kind;
-	return kind == TYPE_DISTINCT || kind == TYPE_CONST_ENUM;
+	return is_distinct_like[type->type_kind];
+}
+
+static bool type_has_inline(Type *type)
+{
+	return is_distinct_like[type->type_kind] && type->decl->is_substruct;
 }
 
 static inline Type *type_inline(Type *type)
 {
 	assert(type_is_distinct_like(type));
-	return type->type_kind == TYPE_CONST_ENUM ? type->decl->enums.type_info->type : type->decl->distinct->type;
+	return type->type_kind == TYPE_DISTINCT ? type->decl->distinct->type : type->decl->enums.type_info->type;
 }
 
 
@@ -3136,16 +3152,8 @@ static inline Type *type_flat_distinct_inline(Type *type)
 	while (1)
 	{
 		type = type->canonical;
-		switch (type->type_kind)
-		{
-			case TYPE_DISTINCT:
-			case TYPE_CONST_ENUM:
-				if (!type->decl->is_substruct) return type;
-				type = type_inline(type);
-				break;
-			default:
-				return type;
-		}
+		if (!type_has_inline(type)) return type;
+		type = type_inline(type);
 	}
 }
 
diff --git a/src/compiler/sema_expr.c b/src/compiler/sema_expr.c
index ab0073481..147d4c0fb 100644
--- a/src/compiler/sema_expr.c
+++ b/src/compiler/sema_expr.c
@@ -1108,7 +1108,7 @@ static inline bool sema_expr_analyse_ternary(SemaContext *context, Type *infer_t
 	Type *right_canonical = right->type->canonical;
 	if (left_canonical != right_canonical)
 	{
-		Type *max = type_find_max_type(type_no_optional(left_canonical), type_no_optional(right_canonical));
+		Type *max = type_find_max_type(type_no_optional(left_canonical), type_no_optional(right_canonical), left, right);
 		if (!max)
 		{
 			SEMA_ERROR(expr, "Cannot find a common parent type of '%s' and '%s'",
@@ -2566,7 +2566,7 @@ static inline Type *context_unify_returns(SemaContext *context)
 		if (common_type == rtype || (type_is_void(common_type) && rtype == type_wildcard)) continue;
 
 		// 4. Find the max of the old and new.
-		Type *max = type_find_max_type(common_type, rtype); // NOLINT
+		Type *max = type_find_max_type(common_type, rtype, NULL, NULL);
 
 		// 5. No match -> error.
 		if (!max)
@@ -4256,7 +4256,7 @@ INLINE bool sema_expr_analyse_range_internal(SemaContext *context, Range *range,
 	if (IS_OPTIONAL(start)) range->is_optional = true;
 	if (end && end_type != start_type)
 	{
-		Type *common = type_find_max_type(start_type, end_type);
+		Type *common = type_find_max_type(start_type, end_type, NULL, NULL);
 		if (!common)
 		{
 			SourceSpan span = start->span;
@@ -7373,7 +7373,7 @@ static bool sema_binary_arithmetic_promotion(SemaContext *context, Expr *left, E
 		}
 	}
 
-	Type *max = cast_numeric_arithmetic_promotion(type_find_max_type(left_type, right_type));
+	Type *max = cast_numeric_arithmetic_promotion(type_find_max_type(left_type, right_type, left, right));
 	if (!max || (!type_underlying_is_numeric(max) && !(allow_bool_vec && type_flat_is_bool_vector(max))))
 	{
 		CHECK_ON_DEFINED(failed_ref);
@@ -8275,7 +8275,7 @@ NEXT:
 
 
 	// 3. In the normal case, treat this as a binary op, finding the max type.
-	Type *max = type_find_max_type(left_type, right_type);
+	Type *max = type_find_max_type(left_type, right_type, left, right);
 
 	// 4. If no common type, then that's an error:
 	if (!max)
@@ -9143,7 +9143,7 @@ static inline bool sema_expr_analyse_or_error(SemaContext *context, Expr *expr,
 	bool add_optional = type_is_optional(else_type);
 	type = type_no_optional(type);
 	else_type = type_no_optional(else_type);
-	Type *common = type_find_max_type(type, else_type);
+	Type *common = type_find_max_type(type, else_type, left, right);
 	if (!common)
 	{
 		CHECK_ON_DEFINED(failed_ref);
diff --git a/src/compiler/types.c b/src/compiler/types.c
index badd41bb2..51bdfa04e 100644
--- a/src/compiler/types.c
+++ b/src/compiler/types.c
@@ -1865,6 +1865,10 @@ Type *type_find_max_num_type(Type *num_type, Type *other_num)
 	ASSERT(kind <= other_kind && "Expected ordering");
 	ASSERT(kind != other_kind);
 
+	// If the other is a vector then we always set that one as the max.
+	if (other_kind == TYPE_VECTOR) return other_num;
+
+
 	// 1. The only conversions need to happen if the other type is a number.
 	if (other_kind < TYPE_INTEGER_FIRST || other_kind > TYPE_FLOAT_LAST) return NULL;
 
@@ -1925,7 +1929,7 @@ static inline Type *type_find_max_ptr_type(Type *type, Type *other)
 	// Slice and vararray can implicitly convert to a pointer.
 	if (other->type_kind == TYPE_SLICE)
 	{
-		Type *max_type = type_find_max_type(type->pointer, other->pointer);
+		Type *max_type = type_find_max_type(type->pointer, other->pointer, false, false);
 		if (!max_type) return NULL;
 		return type_get_ptr(max_type);
 	}
@@ -1959,7 +1963,7 @@ static inline Type *type_find_max_ptr_type(Type *type, Type *other)
 	{
 		return other;
 	}
-	Type *max_type = type_find_max_type(pointer_type, other_pointer_type);
+	Type *max_type = type_find_max_type(pointer_type, other_pointer_type, false, false);
 	if (!max_type) return NULL;
 	return type_get_ptr(max_type);
 }
@@ -2011,57 +2015,97 @@ static inline Type *type_find_max_distinct_type(Type *left, Type *right)
 }
 
 
-Type *type_find_max_type(Type *type, Type *other)
+Type *type_find_max_type(Type *type, Type *other, Expr *first, Expr *second)
 {
 	type = type->canonical;
 	other = other->canonical;
 	ASSERT(!type_is_optional(type) && !type_is_optional(other));
 
 RETRY_DISTINCT:
+	// Same type, max is the type
 	if (type == other) return type;
 
+	// One type is wildcard, max is the type which isn't wildcard
 	if (type == type_wildcard) return other;
 	if (other == type_wildcard) return type;
 
-	// Sort types
+	// Sort types to make it easier
 	if (type->type_kind > other->type_kind)
 	{
 		Type *temp = type;
+		Expr *first_expr = first;
 		type = other;
+		first = second;
 		other = temp;
+		second = first_expr;
 	}
 
-	// The following relies on type kind ordering
+	// The following relies on type kind ordering, with the "lowest" type kind on top, this means the other type kind is
+	// further down in the list
 	switch (type->type_kind)
 	{
-		case TYPE_INFERRED_ARRAY:
-		case TYPE_INFERRED_VECTOR:
 		case TYPE_POISONED:
-		case TYPE_OPTIONAL:
-		case TYPE_WILDCARD:
+			// Should never get here
 			UNREACHABLE
 		case TYPE_VOID:
 		case TYPE_BOOL:
-		case TYPE_TYPEINFO:
-		case TYPE_BITSTRUCT:
-		case TYPE_FLEXIBLE_ARRAY:
+			if (type_has_inline(other))
+			{
+				other = type_flat_distinct_inline(other);
+				goto RETRY_DISTINCT;
+			}
 			return NULL;
 		case ALL_INTS:
-			if (type_is_distinct_like(other) && type_underlying_is_numeric(other)) return other;
-			if (other->type_kind == TYPE_VECTOR) return other;
+		{
+			// If Foo + 1, then we allow this if Foo is a distinct type or const enum that has
+			// integer or float as the base type.
+			if (first && type_is_distinct_like(other) && type_underlying_is_numeric(other) && expr_is_const(first)) return other;
+			// See if we can flatten it.
+			if (type_has_inline(other))
+			{
+				other = type_flat_distinct_inline(other);
+				goto RETRY_DISTINCT;
+			}
+			// Now let's just compare the numerical type, including vectors
 			return type_find_max_num_type(type, other);
+		}
 		case ALL_FLOATS:
-			if (type_is_distinct_like(other) && type_is_float(type_flatten(other))) return other;
-			if (other->type_kind == TYPE_VECTOR) return other;
+		{
+			// If Foo + 1.0, then we allow this if Foo is a distinct type or const enum that has
+			// float as the base type.
+			if (first && type_is_distinct_like(other) && type_underlying_is_numeric(other) && expr_is_const(first)) return other;
+			// See if we can flatten it.
+			if (type_has_inline(other))
+			{
+				other = type_flat_distinct_inline(other);
+				goto RETRY_DISTINCT;
+			}
+			// Now let's just compare the numerical type, including vectors
 			return type_find_max_num_type(type, other);
+		}
 		case TYPE_ANY:
 			// any + interface => any
 			if (other == type_voidptr) return other;
+			if (type_has_inline(other))
+			{
+				other = type_flat_distinct_inline(other);
+				goto RETRY_DISTINCT;
+			}
 			return other->type_kind == TYPE_INTERFACE ? type : NULL;
 		case TYPE_INTERFACE:
 			// interface + void* => void*
+			if (type_has_inline(other))
+			{
+				other = type_flat_distinct_inline(other);
+				goto RETRY_DISTINCT;
+			}
 			return other == type_voidptr ? type_voidptr : NULL;
 		case TYPE_POINTER:
+			if (type_has_inline(other))
+			{
+				other = type_flat_distinct_inline(other);
+				goto RETRY_DISTINCT;
+			}
 			if (type->pointer->type_kind == TYPE_ARRAY)
 			{
 				Type *array_base = type->pointer->array.base->canonical;
@@ -2092,38 +2136,62 @@ RETRY_DISTINCT:
 			// And possibly the other pointer as well
 			if (other->type_kind == TYPE_POINTER) other = type_decay_array_pointer(other);
 			return type_find_max_ptr_type(type, other);
-		case TYPE_ENUM:
-			if (type->decl->is_substruct)
-			{
-				return type_find_max_type(type_flat_distinct_enum_inline(type), other);
-			}
-			return NULL;
 		case TYPE_ANYFAULT:
-			return type_fault;
+		case TYPE_TYPEID:
+			if (type_has_inline(other))
+			{
+				other = type_flat_distinct_inline(other);
+				goto RETRY_DISTINCT;
+			}
+			return type;
 		case TYPE_FUNC_PTR:
 			if (other == type_voidptr) return other;
+			if (type_has_inline(other))
+			{
+				other = type_flat_distinct_inline(other);
+				goto RETRY_DISTINCT;
+			}
 			if (other->type_kind != TYPE_FUNC_PTR) return NULL;
 			if (other->pointer->function.prototype->raw_type != type->pointer->function.prototype->raw_type) return NULL;
 			return type;
+		case TYPE_DISTINCT:
+		case TYPE_CONST_ENUM:
+			if (type_is_distinct_like(other))
+			{
+				return type_find_max_distinct_type(type, other);
+			}
+			// Try matching with its inline type
+			if (type->decl->is_substruct)
+			{
+				type = type_inline(type);
+				goto RETRY_DISTINCT;
+			}
+			// distinct + any other type => no
+			return NULL;
+		case TYPE_ENUM:
+			// Note that the int case is already handled
+			if (type->decl->is_substruct)
+			{
+				return type_find_max_type(type_flat_distinct_enum_inline(type), other, first, second);
+			}
+			return NULL;
 		case TYPE_FUNC_RAW:
 			UNREACHABLE
+		case TYPE_UNION:
+		case TYPE_STRUCT:
+		case TYPE_BITSTRUCT:
+			// union/struct + anything else => no
+			// even if the struct has an inline type, this should not
+			// be implicit
+			return NULL;
+		case TYPE_TYPEDEF:
+			UNREACHABLE // Should only handle canonical types
 		case TYPE_UNTYPED_LIST:
 			if (other->type_kind == TYPE_ARRAY) return other;
 			if (other->type_kind == TYPE_VECTOR) return other;
 			if (other->type_kind == TYPE_STRUCT) return other;
 			if (other->type_kind == TYPE_SLICE) return other;
 			return NULL;
-		case TYPE_UNION:
-		case TYPE_STRUCT:
-			// union/struct + anything else => no
-			// even if the struct has an inline type, this should not
-			// be implicit
-			return NULL;
-		case TYPE_TYPEID:
-		case TYPE_MEMBER:
-			return NULL;
-		case TYPE_TYPEDEF:
-			UNREACHABLE
 		case TYPE_SLICE:
 			// slice + [array, vector of the same type] => yes
 			if (type_is_arraylike(other) && (other->array.base->canonical == type->array.base->canonical))
@@ -2135,27 +2203,24 @@ RETRY_DISTINCT:
 		case TYPE_ARRAY:
 			// array + [other array, vector] => no
 			return NULL;
+		case TYPE_FLEXIBLE_ARRAY:
+		case TYPE_INFERRED_ARRAY:
+		case TYPE_INFERRED_VECTOR:
+			// Already handled
+			UNREACHABLE
+		case TYPE_OPTIONAL:
+			// Should never be passed here
+			UNREACHABLE
+		case TYPE_WILDCARD:
+			// Handled above
+			UNREACHABLE
+		case TYPE_TYPEINFO:
+		case TYPE_MEMBER:
+			return NULL;
+			UNREACHABLE
 		case TYPE_VECTOR:
 			// No implicit conversion between vectors
 			return NULL;
-		case TYPE_DISTINCT:
-		case TYPE_CONST_ENUM:
-			if (type_is_distinct_like(other))
-			{
-				return type_find_max_distinct_type(type, other);
-			}
-			if (other->type_kind == TYPE_ENUM && other->decl->is_substruct)
-			{
-				return type_find_max_type(type, type_flat_distinct_enum_inline(other));
-			}
-			// Try matching with its inline type
-			if (type->decl->is_substruct)
-			{
-				type = type_inline(type);
-				goto RETRY_DISTINCT;
-			}
-			// distinct + any other type => no
-			return NULL;
 	}
 	UNREACHABLE
 }
diff --git a/test/test_suite/expressions/casts/inline_to_underlying.c3t b/test/test_suite/expressions/casts/inline_to_underlying.c3t
new file mode 100644
index 000000000..a2fd1b893
--- /dev/null
+++ b/test/test_suite/expressions/casts/inline_to_underlying.c3t
@@ -0,0 +1,44 @@
+// #target: macos-x64
+module test;
+import std;
+typedef DistinctInt = inline int;
+enum Foo : inline int
+{
+	ABC,
+}
+enum Bar : const inline int
+{
+	HELLO = 1
+}
+fn int main()
+{
+	int a = 1;
+	DistinctInt b = 2;
+	int c = a + b;
+	c = a + Bar.HELLO;
+	c = a + Foo.ABC;
+	return 0;
+}
+
+/* #expect: test.ll
+
+
+define i32 @main() #0 {
+entry:
+  %a = alloca i32, align 4
+  %b = alloca i32, align 4
+  %c = alloca i32, align 4
+  store i32 1, ptr %a, align 4
+  store i32 2, ptr %b, align 4
+  %0 = load i32, ptr %a, align 4
+  %1 = load i32, ptr %b, align 4
+  %add = add i32 %0, %1
+  store i32 %add, ptr %c, align 4
+  %2 = load i32, ptr %a, align 4
+  %add1 = add i32 %2, 1
+  store i32 %add1, ptr %c, align 4
+  %3 = load i32, ptr %a, align 4
+  %add2 = add i32 %3, 0
+  store i32 %add2, ptr %c, align 4
+  ret i32 0
+}
\ No newline at end of file