:: commit 5305dc10ca86b7b58153207c1fcfd43b7633d199

diff --git a/stage23/protos/bootboot/initrd.c b/stage23/protos/bootboot/initrd.c
index 39657f3e..e92f1ac7 100644
--- a/stage23/protos/bootboot/initrd.c
+++ b/stage23/protos/bootboot/initrd.c
@@ -9,26 +9,8 @@ INITRD_HANDLER(jamesm);
 INITRD_HANDLER(ustar);
 INITRD_HANDLER(cpio);
 
-#define DETECT_FAILED panic("bootboot: cannot read file `%s`: cannot detect initrd type (only ustar, cpio and jamesm is supported).", path)
-
 INITRD_HANDLER(auto) {
-    if (file.size < 4) {
-        DETECT_FAILED;
-    }
-
-    if (!memcmp(file.data, "\177ELF", 4)) {
-        if (strcmp("sys/core", path) == 0) {
-            printv("bootboot: using ELF as initrd to open sys/core\n");
-            return file;
-        }
-        return (struct initrd_file){0};
-    }
-
-    if (file.size < 5) {
-        DETECT_FAILED;
-    }
-
-    if (file.data[4] == 0xBF) {
+    if (file.size >= 5 && file.data[4] == 0xbf) {
         struct initrd_file jamesm_attempt = initrd_open_jamesm(file, path);
         if (jamesm_attempt.data) {
             printv("bootboot: jamesm matched when reading file `%s`\n", path);
@@ -37,7 +19,7 @@ INITRD_HANDLER(auto) {
         panic("bootboot: cannot read file `%s`: no such file or directory", path);
     }
 
-    if (!memcmp("07070", file.data, 5)) {
+    if (file.size >= 5 && memcmp("07070", file.data, 5) == 0) {
         struct initrd_file cpio_attempt = initrd_open_cpio(file, path);
         if (cpio_attempt.data) {
             printv("bootboot: cpio matched when reading file `%s`\n", path);
@@ -46,11 +28,7 @@ INITRD_HANDLER(auto) {
         panic("bootboot: cannot read file `%s`: no such file or directory", path);
     }
 
-    if (file.size < 262) {
-        DETECT_FAILED;
-    }
-
-    if (!memcmp("ustar", file.data + 257, 5)) {
+    if (file.size >= 262 && memcmp("ustar", file.data + 257, 5) == 0) {
         struct initrd_file ustar_attempt = initrd_open_ustar(file, path);
         if (ustar_attempt.data) {
             printv("bootboot: ustar matched when reading file `%s`\n", path);
@@ -59,5 +37,17 @@ INITRD_HANDLER(auto) {
         panic("bootboot: cannot read file `%s`: no such file or directory", path);
     }
 
-    DETECT_FAILED;
+    if (strcmp("sys/core", path) == 0) {
+        for (size_t i = 0; i < file.size; i += 4) {
+            if (memcmp(file.data + i, "\177ELF", 4) == 0) {
+                printv("bootboot: using ELF as initrd to open sys/core\n");
+                return (struct initrd_file){
+                    .size = file.size - i,
+                    .data = file.data + i
+                };
+            }
+        }
+    }
+
+    panic("bootboot: cannot read file `%s`: cannot detect initrd type (only ustar, cpio and jamesm is supported).", path);
 }