diff --git a/frontend/cmd/assemble.c b/frontend/cmd/assemble.c
index 4283510..b3cb34a 100644
--- a/frontend/cmd/assemble.c
+++ b/frontend/cmd/assemble.c
@@ -2,13 +2,13 @@
 #include "cmd.h"
 
 #include <blue/cmd.h>
-#include <blue/term.h>
 #include <blue/object/string.h>
+#include <blue/term.h>
 #include <errno.h>
-#include <ivy/file.h>
+#include <ivy/asm/assembler.h>
 #include <ivy/asm/lex.h>
 #include <ivy/asm/parse.h>
-#include <ivy/asm/assembler.h>
+#include <ivy/file.h>
 #include <stdio.h>
 
 enum {
@@ -19,10 +19,13 @@ enum {
 
 static int assemble_file(const char *in_path, const char *out_path)
 {
-	FILE *in = fopen(in_path, "r");
-	if (!in) {
+	enum ivy_status status = IVY_OK;
+
+	struct ivy_file *src = NULL;
+	status = ivy_file_open(in_path, &src);
+	if (!src) {
 		b_err("cannot open source file '%s'", in_path);
-		b_i("reason: %s", strerror(errno));
+		b_i("reason: %s", ivy_status_to_string(status));
 		return -1;
 	}
 
@@ -34,24 +37,23 @@ static int assemble_file(const char *in_path, const char *out_path)
 	}
 
 	struct ivy_assembler *as = NULL;
-	enum ivy_status status = ivy_assembler_create(out, &as);
+	status = ivy_assembler_create(out, &as);
 
 	if (status != IVY_OK) {
 		b_err("failed to initialise Ivy assembler");
 		b_i("reason: %s", ivy_status_to_string(status));
 
-		fclose(in);
+		ivy_file_close(src);
 		fclose(out);
 		return -1;
 	}
 
-	struct ivy_file *src = ivy_file_from_fp(in);
 	struct ivy_asm_lexer *lex;
 	status = ivy_asm_lexer_create(&lex);
 	if (status != IVY_OK) {
 		b_err("failed to initialise Ivy assembly lexer");
 		b_i("reason: %s", ivy_status_to_string(status));
-		
+
 		ivy_file_close(src);
 		fclose(out);
 		ivy_assembler_finish(as);
@@ -101,7 +103,7 @@ static int assemble_file(const char *in_path, const char *out_path)
 	}
 
 	int r = (status == IVY_OK || status == IVY_ERR_EOF) ? 0 : -1;
-	
+
 	ivy_asm_parser_destroy(parser);
 	ivy_assembler_finish(as);
 	ivy_file_close(src);
@@ -120,7 +122,7 @@ static b_string *get_source_filename(const char *src_path)
 			continue;
 		}
 
-		char s[] = { src_path[i], 0 };
+		char s[] = {src_path[i], 0};
 		b_string_append_cstr(name, s);
 	}
 
@@ -140,15 +142,15 @@ static b_string *generate_object_filename(const char *src_filename)
 		if (src_filename[i] == '.') {
 			break;
 		}
-		
-		char s[] = { src_filename[i], 0 };
+
+		char s[] = {src_filename[i], 0};
 		b_string_append_cstr(name, s);
 	}
 
 	if (b_string_get_size(name, B_STRLEN_NORMAL) == 0) {
 		b_string_append_cstr(name, "out");
 	}
-	
+
 	b_string_append_cstr(name, ".io");
 	return name;
 }
@@ -161,12 +163,13 @@ static int assemble(const b_command *cmd, const b_arglist *args, const b_array *
 	b_string *in_name = NULL;
 	b_string *out_name = NULL;
 
-	b_arglist_get_string(args, B_COMMAND_INVALID_ID, ARG_SOURCE_FILE, 0, &in_path);
+	b_arglist_get_string(
+		args, B_COMMAND_INVALID_ID, ARG_SOURCE_FILE, 0, &in_path);
 	if (!in_path) {
 		b_err("no source file specified.");
 		return -1;
 	}
-	
+
 	in_name = get_source_filename(in_path);
 	if (!in_path) {
 		b_err("source filepath is not a file.");
@@ -231,7 +234,8 @@ B_COMMAND(CMD_ASSEMBLE, CMD_ROOT)
 	B_COMMAND_NAME("assemble");
 	B_COMMAND_SHORT_NAME('A');
 	B_COMMAND_DESC(
-		"assemble one or more Ivy assembly source files into Ivy object files.");
+		"assemble one or more Ivy assembly source files into Ivy "
+		"object files.");
 	B_COMMAND_FLAGS(B_COMMAND_SHOW_HELP_BY_DEFAULT);
 	B_COMMAND_FUNCTION(assemble);
 
@@ -247,7 +251,8 @@ B_COMMAND(CMD_ASSEMBLE, CMD_ROOT)
 		B_OPTION_SHORT_NAME('o');
 		B_OPTION_LONG_NAME("out");
 		B_OPTION_DESC("the path to write the output binary file to.");
-		B_OPTION_ARG(ARG_OUT_FILE) {
+		B_OPTION_ARG(ARG_OUT_FILE)
+		{
 			B_ARG_NAME("path");
 			B_ARG_NR_VALUES(1);
 		}
diff --git a/frontend/cmd/compile.c b/frontend/cmd/compile.c
index ea161c8..dc2db36 100644
--- a/frontend/cmd/compile.c
+++ b/frontend/cmd/compile.c
@@ -4,9 +4,11 @@
 #include <blue/cmd.h>
 #include <blue/term.h>
 #include <errno.h>
+#include <ivy/diag.h>
 #include <ivy/file.h>
 #include <ivy/lang/ast.h>
 #include <ivy/lang/codegen.h>
+#include <ivy/lang/diag.h>
 #include <ivy/lang/lex.h>
 #include <mie/convert.h>
 #include <mie/ctx.h>
@@ -52,15 +54,30 @@ static int compile_file(const char *path, const b_arglist *args)
 	              > 0;
 	bool show_ir
 		= b_arglist_get_count(args, OPT_SHOW_IR, B_COMMAND_INVALID_ID) > 0;
+	enum ivy_status status = IVY_OK;
 
-	FILE *fp = fopen(path, "r");
-	if (!fp) {
+	struct ivy_file *src = NULL;
+	status = ivy_file_open(path, &src);
+	if (!src) {
 		b_err("cannot open source file '%s'", path);
-		b_i("reason: %s", strerror(errno));
+		b_i("reason: %s", ivy_status_to_string(status));
 		return -1;
 	}
 
-	struct ivy_file *src = ivy_file_from_fp(fp);
+	struct ivy_diag_stream diag_stream;
+	ivy_diag_stream_init_tty(&diag_stream, b_stdtty);
+
+	struct ivy_diag_ctx *diag = NULL;
+	status = ivy_diag_ctx_create(&diag);
+	if (status != IVY_OK) {
+		b_err("failed to initialise Ivy diagnostic context");
+		ivy_file_close(src);
+		return -1;
+	}
+
+	ivy_lang_diag_ctx_init(diag);
+	ivy_diag_ctx_set_line_source(diag, &src->f_base);
+
 	struct ivy_lexer *lex = NULL;
 	if (ivy_lexer_create(&lex) != IVY_OK) {
 		b_err("failed to initialise Ivy lexer");
@@ -69,7 +86,7 @@ static int compile_file(const char *path, const b_arglist *args)
 	}
 
 	ivy_lexer_set_source(lex, &src->f_base);
-	enum ivy_status status = IVY_OK;
+	ivy_lexer_set_diag_ctx(lex, diag);
 
 	struct ivy_parser *parser = NULL;
 	status = ivy_parser_create(&parser);
@@ -102,9 +119,13 @@ static int compile_file(const char *path, const b_arglist *args)
 		}
 
 		if (status != IVY_OK) {
+			ivy_diag_ctx_write(
+				diag, IVY_DIAG_FORMAT_PRETTY, &diag_stream);
+#if 0
 			b_err("failed to parse '%s'", path);
 			b_i("reason: lex error (%s)",
 			    ivy_status_to_string(ivy_lexer_get_status(lex)));
+#endif
 			break;
 		}