diff --git a/funcs/histogram.c b/funcs/histogram.c
index 322e3f0f..f10118cd 100644
--- a/funcs/histogram.c
+++ b/funcs/histogram.c
@@ -48,37 +48,43 @@ return -66;
 }
 /* --------------------------------------------------------------------- */
 
-#define NSLICES 1000
-
-int fimg_essai_histo(FloatImg *src, char *outpic, int k)
+int fimg_essai_histo(FloatImg *src, char *outpic, int nbslices)
 {
-long		histo[NSLICES];
+long		*histo;
 int		foo;
 FILE		*pipe;
 
-fprintf(stderr, ">>> %s ( %p '%s' %d )\n", __func__, src, outpic, k);
+fprintf(stderr, ">>> %s ( %p '%s' %d )\n", __func__, src, outpic, nbslices);
 
-memset(histo, 0, NSLICES*sizeof(long));
+if (NULL==(histo=calloc(nbslices, sizeof(long)))) {
+	fprintf(stderr, "OUT OF MEMORY\n");
+	abort();
+	}
 
-foo = fimg_calcul_histo(src, histo, NSLICES);
+foo = fimg_calcul_histo(src, histo, nbslices);
 
 // for (foo=0; foo<NSLICES; foo++)	{
 //	printf("%7d   %ld\n", foo, histo[foo]);
 //	}
 
 pipe = popen("gnuplot", "w");
+if (NULL==pipe) {
+	fprintf(stderr, "%s: error running gnuplot\n", __func__);
+	return -17;
+	}
 fprintf(pipe, "set term png    size 1024,512\n");
 fprintf(pipe, "set grid\n");
 fprintf(pipe, "set output \"%s\"\n", outpic);
 fprintf(pipe, "plot '/dev/stdin' with lines\n");
 
-for (foo=0; foo<NSLICES; foo++)	{
+for (foo=0; foo<nbslices; foo++)	{
 	fprintf(pipe, "%d %ld\n", foo, histo[foo]);
 	}
 
-fclose(pipe);
+pclose(pipe);		// and not fclose (see man page)
 
+free(histo);
 
-return -1;
+return 0;
 }
 /* --------------------------------------------------------------------- */
diff --git a/funcs/t.c b/funcs/t.c
index 83ac193c..0805507b 100644
--- a/funcs/t.c
+++ b/funcs/t.c
@@ -409,6 +409,7 @@ int essai_histogramme(char *fname, int k)
 {
 FloatImg	fimg;
 int		foo;
+
 fprintf(stderr, ">>> %s ( '%s' %d )\n", __func__, fname, k);
 
 foo = fimg_create_from_dump(fname, &fimg);
@@ -419,13 +420,15 @@ if (foo) {
 
 foo = fimg_essai_histo(&fimg, "out.png", k);
 if (foo) {
-	fprintf(stderr, "essai_histo -> %d\n", foo);
+	fprintf(stderr, "essai_histo -> error %d\n", foo);
 	return foo;
 	}
 
+fimg_destroy(&fimg);
+
 fprintf(stderr, "\\o/ end of %s\n", __func__);
 
-return -1;
+return 0;
 }
 /* --------------------------------------------------------------------- */
 enum nCmd { Equalize=1, Rotate, Sfx0, F3x3, MIRE, Wfits, Wpng, Wtiff,
@@ -536,7 +539,7 @@ switch(opt) {
 		foo = essai_ecriture_tiff(filename);
 		break;
 	case Histo:
-		foo = essai_histogramme(filename, 0);
+		foo = essai_histogramme(filename, 98765);
 		break;
 	default:
 		fprintf(stderr, "%s : bad command\n", command);