diff --git a/ui-blob.c b/ui-blob.c
index 3cda03d..2ccd31d 100644
--- a/ui-blob.c
+++ b/ui-blob.c
@@ -27,7 +27,7 @@ void cgit_print_blob(const char *hex, char *path, const char *head)
 
 	unsigned char sha1[20];
 	enum object_type type;
-	unsigned char *buf;
+	char *buf;
 	unsigned long size;
 	struct commit *commit;
 	const char *paths[] = {path, NULL};
@@ -67,6 +67,12 @@ void cgit_print_blob(const char *hex, char *path, const char *head)
 
 	buf[size] = '\0';
 	ctx.page.mimetype = ctx.qry.mimetype;
+	if (!ctx.page.mimetype) {
+		if (buffer_is_binary(buf, size))
+			ctx.page.mimetype = "application/octet-stream";
+		else
+			ctx.page.mimetype = "text/plain";
+	}
 	ctx.page.filename = path;
 	cgit_print_http_headers(&ctx);
 	write(htmlfd, buf, size);
diff --git a/ui-plain.c b/ui-plain.c
index 5addd9e..9a9ae7d 100644
--- a/ui-plain.c
+++ b/ui-plain.c
@@ -31,7 +31,10 @@ static void print_object(const unsigned char *sha1, const char *path)
 		html_status(404, "Not found", 0);
 		return;
 	}
-	ctx.page.mimetype = "text/plain";
+	if (buffer_is_binary(buf, size))
+		ctx.page.mimetype = "application/octet-stream";
+	else
+		ctx.page.mimetype = "text/plain";
 	ctx.page.filename = fmt("%s", path);
 	ctx.page.size = size;
 	cgit_print_http_headers(&ctx);