diff --git a/imagery/i.cca/main.c b/imagery/i.cca/main.c
index 22ccd2058a0..6aee7b0e631 100644
--- a/imagery/i.cca/main.c
+++ b/imagery/i.cca/main.c
@@ -156,10 +156,10 @@ int main(int argc, char *argv[])
         cov[i] = G_alloc_matrix(bands, bands);
     }
 
-    outbandmax = (CELL *)G_calloc(nclass, sizeof(CELL));
-    outbandmin = (CELL *)G_calloc(nclass, sizeof(CELL));
-    datafds = (int *)G_calloc(nclass, sizeof(int));
-    outfds = (int *)G_calloc(nclass, sizeof(int));
+    outbandmax = (CELL *)G_calloc(bands, sizeof(CELL));
+    outbandmin = (CELL *)G_calloc(bands, sizeof(CELL));
+    datafds = (int *)G_calloc(bands, sizeof(int));
+    outfds = (int *)G_calloc(bands, sizeof(int));
 
     /*
        Here is where the information regarding
@@ -169,13 +169,14 @@ int main(int argc, char *argv[])
      */
 
     samptot = 0;
-    for (i = 1; i <= nclass; i++) {
-        nsamp[i] = sigs.sig[i - 1].npoints;
+    for (i = 0; i < nclass; i++) {
+        nsamp[i] = sigs.sig[i].npoints;
         samptot += nsamp[i];
-        for (j = 1; j <= bands; j++) {
-            mu[i][j] = sigs.sig[i - 1].mean[j - 1];
-            for (k = 1; k <= j; k++)
-                cov[i][j][k] = cov[i][k][j] = sigs.sig[i - 1].var[j - 1][k - 1];
+        for (j = 0; j < bands; j++) {
+            mu[i][j] = sigs.sig[i].mean[j];
+            for (k = 0; k <= j; k++) {
+                cov[i][j][k] = cov[i][k][j] = sigs.sig[i].var[j][k];
+            }
         }
     }
 
@@ -200,14 +201,13 @@ int main(int argc, char *argv[])
     }
 
     /* open the cell maps */
-    for (i = 1; i <= bands; i++) {
+    for (i = 0; i < bands; i++) {
         outbandmax[i] = (CELL)0;
         outbandmin[i] = (CELL)0;
 
-        datafds[i] =
-            Rast_open_old(refs.file[i - 1].name, refs.file[i - 1].mapset);
+        datafds[i] = Rast_open_old(refs.file[i].name, refs.file[i].mapset);
 
-        sprintf(tempname, "%s.%d", out_opt->answer, i);
+        sprintf(tempname, "%s.%d", out_opt->answer, i + 1);
         outfds[i] = Rast_open_c_new(tempname);
     }
 
@@ -219,7 +219,7 @@ int main(int argc, char *argv[])
     Rast_init_colors(&color_tbl);
 
     /* close the cell maps */
-    for (i = 1; i <= bands; i++) {
+    for (i = 0; i < bands; i++) {
         Rast_close(datafds[i]);
         Rast_close(outfds[i]);
 
diff --git a/imagery/i.cca/testsuite/test_i_cca.py b/imagery/i.cca/testsuite/test_i_cca.py
new file mode 100644
index 00000000000..4049274e5f8
--- /dev/null
+++ b/imagery/i.cca/testsuite/test_i_cca.py
@@ -0,0 +1,92 @@
+"""
+Name:      i.cca tests
+Purpose:   Test correctness of generated outputs
+
+Author:    Maris Nartiss
+Copyright: (C) 2023 by Maris Nartiss and the GRASS Development Team
+Licence:   This program is free software under the GNU General Public
+           License (>=v2). Read the file COPYING that comes with GRASS
+           for details.
+"""
+
+from grass.script.core import tempname
+
+from grass.gunittest.case import TestCase
+from grass.gunittest.main import test
+
+
+class OutputMatchTest(TestCase):
+    """
+    Compare values to output generated by pre-7.0 version of the module.
+    Comparison values were obtained with pre-ccmath rewrite version
+    664305e4b8de924c8dfb5385e8bf6c18fbf649be
+    """
+
+    @classmethod
+    def setUpClass(cls):
+        """Ensures expected computational region and generated data"""
+        cls.use_temp_region()
+        cls.runModule("g.region", raster="lsat7_2000_20")
+        cls.group_name = tempname(10)
+        cls.subgroup_name = "vis"
+        cls.runModule(
+            "i.group",
+            group=cls.group_name,
+            subgroup=cls.subgroup_name,
+            input="lsat7_2000_20,lsat7_2000_30,lsat7_2000_40",
+        )
+        cls.rasters = []
+        cls.signatures = []
+
+    @classmethod
+    def tearDownClass(cls):
+        """Remove the temporary region and generated data"""
+        cls.del_temp_region()
+        cls.runModule(
+            "g.remove", flags="f", type="group", name=cls.group_name, quiet=True
+        )
+        for r in cls.rasters:
+            cls.runModule("g.remove", flags="f", type="raster", name=r, quiet=True)
+        for s in cls.signatures:
+            cls.runModule("i.signatures", type="sig", remove=s, quiet=True)
+
+    def test_output_values(self):
+        """Test correctness of i.cca output"""
+        sig_name = tempname(10)
+        self.assertModule(
+            "i.cluster",
+            classes=4,
+            group=self.group_name,
+            subgroup=self.subgroup_name,
+            signaturefile=sig_name,
+            quiet=True,
+        )
+        self.signatures.append(sig_name)
+        out_prefix = tempname(10)
+        self.assertModule(
+            "i.cca",
+            group=self.group_name,
+            subgroup=self.subgroup_name,
+            signature=sig_name,
+            output=out_prefix,
+            quiet=True,
+        )
+        self.assertRasterExists(f"{out_prefix}.1")
+        self.rasters.append(f"{out_prefix}.1")
+        self.assertRasterExists(f"{out_prefix}.2")
+        self.rasters.append(f"{out_prefix}.2")
+        self.assertRasterExists(f"{out_prefix}.3")
+        self.rasters.append(f"{out_prefix}.3")
+        self.assertRasterMinMax(
+            map=f"{out_prefix}.1", refmin=-10, refmax=9, msg="Wrong calculated value"
+        )
+        self.assertRasterMinMax(
+            map=f"{out_prefix}.2", refmin=-34, refmax=-3, msg="Wrong calculated value"
+        )
+        self.assertRasterMinMax(
+            map=f"{out_prefix}.3", refmin=-24, refmax=5, msg="Wrong calculated value"
+        )
+
+
+if __name__ == "__main__":
+    test()