diff -Nupr a/squashfs-tools/mksquashfs.c b/squashfs-tools/mksquashfs.c
--- a/squashfs-tools/mksquashfs.c	2020-10-30 06:13:56.000000000 -0500
+++ b/squashfs-tools/mksquashfs.c	2022-01-12 10:58:37.704782953 -0600
@@ -290,6 +290,7 @@ int all_time_opt = FALSE;
 int clamping = TRUE;
 
 /* user options that control parallelisation */
+#define MAX_CPUS 256
 int processors = -1;
 int bwriter_size;
 
@@ -4385,6 +4386,10 @@ void initialise_threads(int readq, int f
 #endif
 	}
 
+	/* Limit the number of processors we're going to use */
+	if(processors > MAX_CPUS)
+		processors = MAX_CPUS;
+
 	if(multiply_overflow(processors, 3) ||
 			multiply_overflow(processors * 3, sizeof(pthread_t)))
 		BAD_ERROR("Processors too large\n");