diff --git a/src/util.c b/src/util.c
index 016057d..44ce61f 100644
--- a/src/util.c
+++ b/src/util.c
@@ -817,7 +817,8 @@ analyze_hunk (struct change *hunk,
       for (i = next->line0; i <= l0 && trivial; i++)
 	{
 	  char const *line = linbuf0[i];
-	  char const *newline = linbuf0[i + 1] - 1;
+	  char const *lastbyte = linbuf0[i + 1] - 1;
+	  char const *newline = lastbyte + (*lastbyte != '\n');
 	  size_t len = newline - line;
 	  char const *p = line;
 	  if (skip_white_space)
@@ -837,7 +838,8 @@ analyze_hunk (struct change *hunk,
       for (i = next->line1; i <= l1 && trivial; i++)
 	{
 	  char const *line = linbuf1[i];
-	  char const *newline = linbuf1[i + 1] - 1;
+	  char const *lastbyte = linbuf1[i + 1] - 1;
+	  char const *newline = lastbyte + (*lastbyte != '\n');
 	  size_t len = newline - line;
 	  char const *p = line;
 	  if (skip_white_space)
diff --git a/tests/no-newline-at-eof b/tests/no-newline-at-eof
index 14d5f49..f503718 100755
--- a/tests/no-newline-at-eof
+++ b/tests/no-newline-at-eof
@@ -50,4 +50,10 @@ compare exp2 out || fail=1
 # expect empty stderr
 compare /dev/null err || fail=1
 
+# Test for Bug#18402.
+printf a > a
+printf b > b
+diff -B a b > out 2>err
+test $? = 1 || fail=1
+
 Exit $fail