diff --git a/diffcore-pickaxe.c b/diffcore-pickaxe.c
index ed23eb4bdd..a209376354 100644
--- a/diffcore-pickaxe.c
+++ b/diffcore-pickaxe.c
@@ -104,10 +104,10 @@ static int diff_grep(struct diff_filepair *p, struct diff_options *o,
 		if (!mf2.ptr)
 			return 0; /* ignore unmerged */
 		/* created "two" -- does it have what we are looking for? */
-		hit = !regexec(regexp, p->two->data, 1, &regmatch, 0);
+		hit = !regexec(regexp, mf2.ptr, 1, &regmatch, 0);
 	} else if (!mf2.ptr) {
 		/* removed "one" -- did it have what we are looking for? */
-		hit = !regexec(regexp, p->one->data, 1, &regmatch, 0);
+		hit = !regexec(regexp, mf1.ptr, 1, &regmatch, 0);
 	} else {
 		/*
 		 * We have both sides; need to run textual diff and see if
diff --git a/t/t4030-diff-textconv.sh b/t/t4030-diff-textconv.sh
index eebb1eed8b..461d27ac20 100755
--- a/t/t4030-diff-textconv.sh
+++ b/t/t4030-diff-textconv.sh
@@ -84,6 +84,18 @@ test_expect_success 'status -v produces text' '
 	git reset --soft HEAD@{1}
 '
 
+test_expect_success 'grep-diff (-G) operates on textconv data (add)' '
+	echo one >expect &&
+	git log --root --format=%s -G0 >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'grep-diff (-G) operates on textconv data (modification)' '
+	echo two >expect &&
+	git log --root --format=%s -G1 >actual &&
+	test_cmp expect actual
+'
+
 cat >expect.stat <<'EOF'
  file | Bin 2 -> 4 bytes
  1 file changed, 0 insertions(+), 0 deletions(-)