diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..cd4cab8
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module git.chromaticdragon.app/kistaro/uckf
+
+go 1.21.4
diff --git a/uckf.go b/uckf.go
index 9479c4b..97981a1 100644
--- a/uckf.go
+++ b/uckf.go
@@ -95,7 +95,7 @@ func isStillFucked(board [][]byte, evals[][]fuckness) bool {
 						// mark every letter involved as fucked
 						isFucked = true
 						for w := 0; w < 4; w++ {
-							evals[i+w*dr][j+w*dc][dr+1][dc+1] = Fucked
+							evals[fRow+w*dr][fCol+w*dc][dr+1][dc+1] = Fucked
 						}
 					} else {
 						evals[i][j][dr+1][dc+1] = NotFucked