diff --git a/src/spasm_certificate.c b/src/spasm_certificate.c
index c5aa5ae..ae7f3a7 100644
--- a/src/spasm_certificate.c
+++ b/src/spasm_certificate.c
@@ -260,12 +260,12 @@ bool spasm_rank_certificate_load(FILE *f, struct spasm_rank_certificate *proof)
 		proof->hash[i] = strtoul(byte, NULL, 16);
 	}
 	for (int k = 0; k < r; k++)
-		fscanf(f, "%d", &proof->i[k]);
+		if (1 != fscanf(f, "%d", &proof->i[k])) return 0;
 	for (int k = 0; k < r; k++)
-		fscanf(f, "%d", &proof->i[k]);
+		if (1 != fscanf(f, "%d", &proof->i[k])) return 0;
 	for (int k = 0; k < r; k++)
-		fscanf(f, "%d", &proof->x[k]);
+		if (1 != fscanf(f, "%d", &proof->x[k])) return 0;
 	for (int k = 0; k < r; k++)
-		fscanf(f, "%d", &proof->y[k]);
+		if (1 != fscanf(f, "%d", &proof->y[k])) return 0;
 	return 1;
-}
\ No newline at end of file
+}
diff --git a/tools/kernel.c b/tools/kernel.c
index 6488f22..fab5454 100644
--- a/tools/kernel.c
+++ b/tools/kernel.c
@@ -3,6 +3,7 @@
 #include <assert.h>
 #include <getopt.h>
 #include <err.h>
+#include <string.h>
 
 #include "spasm.h"
 #include "common.h"
@@ -10,6 +11,8 @@
 /* Program documentation. */
 char doc[] = "Compute a kernel basis of a sparse matrix";
 
+char qinv_filename[1000]; /* we should put this in cmdline_args. Here we use that it's 0-initialized so we both know if it was set and where to write */
+
 struct cmdline_args {
 	/* input problem */
 	struct input_matrix input;
@@ -27,6 +30,7 @@ struct argp_option options[] = {
 	{0,               0,  0,      0, "Kernel options", 2 },
 	{"left",         'l', 0,      0, "Compute the left-kernel", 2},
 	{"output",       'o', "FILE", 0, "Write the kernel basis in FILE", 2 },
+	{"qinv-file",    'q', "FILE", 0, "Save qinv", 2 },
 	{ 0 }
 };
 
@@ -41,6 +45,9 @@ error_t parse_ker_opt(int key, char *arg, struct argp_state *state)
 	case 'o':
 		arguments->output_filename = arg;
 		break;
+	case 'q':
+		strcpy(qinv_filename, arg);
+		break;
 	case ARGP_KEY_INIT:
 		arguments->left = 0;
 		arguments->output_filename = NULL;
@@ -82,10 +89,17 @@ int main(int argc, char **argv)
 	struct spasm_lu *fact = spasm_echelonize(A, &args.opts);
 	spasm_csr_free(A);
 
+	if (qinv_filename[0]) { /* save qinv */
+		FILE *qinv_stream = fopen(qinv_filename,"w");
+		for (int i = 0; i < fact->U->m; i++)
+			fprintf(qinv_stream,"%d\n",fact->qinv[i]);
+		fclose(qinv_stream);
+	}
+
 	/* kernel basis */
 	struct spasm_csr *K = spasm_kernel(fact);
 	fprintf(stderr, "Kernel basis matrix is %d x %d with %" PRId64 " nz\n", K->n, K->m, spasm_nnz(K));
 	
 	FILE *f = open_output(args.output_filename);
 	spasm_csr_save(K, f);
-}
\ No newline at end of file
+}