diff --git a/releasenotes.md b/releasenotes.md
index cd7b94925..38c79be37 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -69,6 +69,7 @@
 - Missing end padding when including a packed struct #1966.
 - Issue when scalar expanding a boolean from a conditional to a bool vector #1954.
 - Fix issue when parsing bitstructs, preventing them from implementing interfaces.
+- Regression `String! a; char* b = a.ptr;` would incorrectly be allowed.
 
 ### Stdlib changes
 - Added '%h' and '%H' for printing out binary data in hexadecimal using the formatter.
diff --git a/src/compiler/compiler_internal.h b/src/compiler/compiler_internal.h
index 7f07edda6..ea291741a 100644
--- a/src/compiler/compiler_internal.h
+++ b/src/compiler/compiler_internal.h
@@ -3784,7 +3784,7 @@ INLINE void expr_rewrite_ptr_access(Expr *expr, Expr *inner, Type *type)
 	ASSERT(inner->resolve_status == RESOLVE_DONE);
 	expr->expr_kind = EXPR_PTR_ACCESS;
 	expr->inner_expr = inner;
-	expr->type = type;
+	expr->type = type_add_optional(type, IS_OPTIONAL(inner));
 	expr->resolve_status = RESOLVE_DONE;
 }
 
@@ -3794,7 +3794,7 @@ INLINE void expr_rewrite_enum_from_ord(Expr *expr, Type *type)
 	ASSERT(inner->resolve_status == RESOLVE_DONE);
 	expr->expr_kind = EXPR_ENUM_FROM_ORD;
 	expr->inner_expr = inner;
-	expr->type = type;
+	expr->type = type_add_optional(type, IS_OPTIONAL(expr));
 	expr->resolve_status = RESOLVE_DONE;
 }
 
@@ -3819,7 +3819,7 @@ INLINE void expr_rewrite_int_to_bool(Expr *expr, bool negate)
 	Expr *inner = expr_copy(expr);
 	expr->expr_kind = EXPR_INT_TO_BOOL;
 	expr->int_to_bool_expr = (ExprIntToBool) { .inner = inner, .negate = negate };
-	expr->type = type_bool;
+	expr->type = type_add_optional(type_bool, IS_OPTIONAL(expr));
 }
 
 INLINE void expr_rewrite_ext_trunc(Expr *expr, Type *type, bool is_signed)
@@ -3827,7 +3827,7 @@ INLINE void expr_rewrite_ext_trunc(Expr *expr, Type *type, bool is_signed)
 	Expr *inner = expr_copy(expr);
 	expr->expr_kind = EXPR_EXT_TRUNC;
 	expr->ext_trunc_expr = (ExprExtTrunc) { .inner = inner, .is_signed = is_signed };
-	expr->type = type;
+	expr->type = type_add_optional(type, IS_OPTIONAL(inner));
 }
 
 INLINE void expr_rewrite_const_int(Expr *expr, Type *type, uint64_t v)
@@ -3869,7 +3869,7 @@ INLINE void expr_rewrite_to_int_to_float(Expr *expr, Type *type)
 	Expr *inner = expr_copy(expr);
 	expr->expr_kind = EXPR_INT_TO_FLOAT;
 	expr->inner_expr = inner;
-	expr->type = type;
+	expr->type = type_add_optional(type, IS_OPTIONAL(inner));
 }
 
 INLINE void expr_rewrite_to_int_to_ptr(Expr *expr, Type *type)
@@ -3877,7 +3877,7 @@ INLINE void expr_rewrite_to_int_to_ptr(Expr *expr, Type *type)
 	Expr *inner = expr_copy(expr);
 	expr->expr_kind = EXPR_INT_TO_PTR;
 	expr->inner_expr = inner;
-	expr->type = type;
+	expr->type = type_add_optional(type, IS_OPTIONAL(inner));
 }
 
 INLINE void expr_rewrite_to_ptr_to_int(Expr *expr, Type *type)
@@ -3885,7 +3885,7 @@ INLINE void expr_rewrite_to_ptr_to_int(Expr *expr, Type *type)
 	Expr *inner = expr_copy(expr);
 	expr->expr_kind = EXPR_PTR_TO_INT;
 	expr->inner_expr = inner;
-	expr->type = type;
+	expr->type = type_add_optional(type, IS_OPTIONAL(inner));
 }
 
 INLINE void expr_rewrite_to_float_to_int(Expr *expr, Type *type)
@@ -3893,7 +3893,7 @@ INLINE void expr_rewrite_to_float_to_int(Expr *expr, Type *type)
 	Expr *inner = expr_copy(expr);
 	expr->expr_kind = EXPR_FLOAT_TO_INT;
 	expr->inner_expr = inner;
-	expr->type = type;
+	expr->type = type_add_optional(type, IS_OPTIONAL(inner));
 }
 
 INLINE void expr_rewrite_const_float(Expr *expr, Type *type, Real d)
@@ -4108,9 +4108,11 @@ INLINE bool check_module_name(Path *path)
 #ifdef NDEBUG
 #define ASSERT_SPANF(node__, check__, format__, ...) do { } while(0)
 #define ASSERT_SPAN(node__, check__) do { } while(0)
+#define ASSERT_AT(span__, check__) do { } while(0)
 #else
 #define ASSERT_SPANF(node__, check__, format__, ...) do { if (!(check__)) { assert_print_line((node__)->span); eprintf(format__, __VA_ARGS__); ASSERT(check__); } } while(0)
 #define ASSERT_SPAN(node__, check__) do { if (!(check__)) { assert_print_line((node__)->span); ASSERT(check__); } } while(0)
+#define ASSERT_AT(span__, check__) do { if (!(check__)) { assert_print_line(span__); ASSERT(check__); } } while(0)
 #endif
 void assert_print_line(SourceSpan span);
 
diff --git a/src/compiler/llvm_codegen_value.c b/src/compiler/llvm_codegen_value.c
index 8a45903a6..7d1dcb674 100644
--- a/src/compiler/llvm_codegen_value.c
+++ b/src/compiler/llvm_codegen_value.c
@@ -115,7 +115,7 @@ void llvm_value_rvalue(GenContext *c, BEValue *value)
 
 void llvm_emit_jump_to_optional_exit(GenContext *c, LLVMValueRef opt_value)
 {
-	ASSERT(c->catch.block && "unexpected emit");
+	ASSERT_AT(c->last_emitted_loc, c->catch.block && "unexpected emit");
 	bool is_constant_opt = llvm_is_const(opt_value);
 
 	// Maybe we don't need to emit anything?
diff --git a/src/compiler/sema_expr.c b/src/compiler/sema_expr.c
index f1f0e50fe..1d72fd92a 100644
--- a/src/compiler/sema_expr.c
+++ b/src/compiler/sema_expr.c
@@ -255,23 +255,24 @@ static inline void context_switch_stat_pop(SemaContext *swapped, ContextSwitchSt
 
 Expr *sema_enter_inline_member(Expr *parent, CanonicalType *type)
 {
+	Expr *expr;
 	switch (type->type_kind)
 	{
 		case TYPE_STRUCT:
 		{
 			Decl *decl = type->decl;
 			if (!decl->is_substruct) return NULL;
-			Expr *embedded_struct = expr_access_inline_member(parent, decl);
-			return embedded_struct;
+			expr = expr_access_inline_member(parent, decl);
+			break;
 		}
 		case TYPE_DISTINCT:
 		{
 			Decl *decl = type->decl;
 			if (!decl->is_substruct) return NULL;
-			Expr *inner_expr = expr_copy(parent);
+			expr = expr_copy(parent);
 			type = type->decl->distinct->type;
-			inner_expr->type = type;
-			return inner_expr;
+			expr->type = type;
+			break;
 		}
 		case TYPE_ENUM:
 		{
@@ -282,28 +283,31 @@ Expr *sema_enter_inline_member(Expr *parent, CanonicalType *type)
 			{
 				if (decl->enums.inline_value)
 				{
-					Expr *expr = expr_new_expr(EXPR_CONST, parent);
+					expr = expr_new_expr(EXPR_CONST, parent);
 					expr_rewrite_const_int(expr, decl->enums.type_info->type, parent->const_expr.enum_err_val->enum_constant.ordinal);
 					return expr;
 				}
-				return copy_expr_single(parent->const_expr.enum_err_val->enum_constant.args[decl->enums.inline_index]);
+				expr = copy_expr_single(parent->const_expr.enum_err_val->enum_constant.args[decl->enums.inline_index]);
+				break;
 			}
 			if (decl->enums.inline_value)
 			{
-				Expr *expr = copy_expr_single(parent);
-				expr->type = decl->enums.type_info->type;
-				return expr;
+				expr = copy_expr_single(parent);
+				expr->type = type_add_optional(decl->enums.type_info->type, IS_OPTIONAL(parent));
+				break;
 			}
-			Expr *property = expr_new(EXPR_ACCESS_RESOLVED, parent->span);
-			property->resolve_status = RESOLVE_DONE;
-			property->access_resolved_expr.parent = parent;
-			property->access_resolved_expr.ref = decl->enums.parameters[decl->enums.inline_value];
-			property->type = property->access_resolved_expr.ref->type;
-			return property;
+			expr = expr_new(EXPR_ACCESS_RESOLVED, parent->span);
+			expr->resolve_status = RESOLVE_DONE;
+			expr->access_resolved_expr.parent = parent;
+			expr->access_resolved_expr.ref = decl->enums.parameters[decl->enums.inline_value];
+			expr->type = expr->access_resolved_expr.ref->type;
+			break;
 		}
 		default:
 			return NULL;
 	}
+	if (IS_OPTIONAL(parent)) expr->type = type_add_optional(expr->type, true);
+	return expr;
 }
 
 Expr *sema_expr_analyse_ct_arg_index(SemaContext *context, Expr *index_expr, unsigned *index_ref)
@@ -406,7 +410,7 @@ Expr *expr_access_inline_member(Expr *parent, Decl *parent_decl)
 	embedded_struct->resolve_status = RESOLVE_DONE;
 	embedded_struct->access_resolved_expr.parent = parent;
 	embedded_struct->access_resolved_expr.ref = parent_decl->strukt.members[0];
-	embedded_struct->type = embedded_struct->access_resolved_expr.ref->type;
+	embedded_struct->type = type_add_optional(embedded_struct->access_resolved_expr.ref->type, IS_OPTIONAL(parent));
 	return embedded_struct;
 }
 
diff --git a/src/compiler/sema_initializers.c b/src/compiler/sema_initializers.c
index bffe22a3b..91457bab1 100644
--- a/src/compiler/sema_initializers.c
+++ b/src/compiler/sema_initializers.c
@@ -480,8 +480,8 @@ static inline bool sema_expr_analyse_untyped_initializer(SemaContext *context, E
 		{
 			RETURN_SEMA_ERROR(element, "An untyped list can only have "
 									   "constant elements, you can try "
-									   "to type the list by prefixing the type, "
-									   "e.g. 'int[2] { a, b }'.");
+									   "to type the list by prefixing the type and possibly enclosing it in parentheses, "
+									   "e.g. '((int[2]){ a, b })'.");
 		}
 	}
 	initializer->expr_kind = EXPR_CONST;
diff --git a/test/test_suite/expressions/opt_in_conv.c3 b/test/test_suite/expressions/opt_in_conv.c3
new file mode 100644
index 000000000..3989ac32b
--- /dev/null
+++ b/test/test_suite/expressions/opt_in_conv.c3
@@ -0,0 +1,9 @@
+module test;
+import std;
+fn void main()
+{
+	String s = "Hello";
+	Char16* title = String.to_new_utf16(s).ptr; // #error: It is not possible to cast from
+	int! a;
+	float b = (float)a; // #error: It is not possible to cast from
+}
\ No newline at end of file