diff --git a/CHANGES.rst b/CHANGES.rst
index cba441a..44b6c3b 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,7 +1,8 @@
 1.8.0 (unreleased)
 ==================
 
-- No changes yet.
+- Fixing ``FLOAT_CMP`` not comparing complex numbers with a negative
+  imaginary part, like ``(1.5-2.5j)``. [#328]
 
 1.7.1 (2026-01-26)
 ==================
diff --git a/pytest_doctestplus/output_checker.py b/pytest_doctestplus/output_checker.py
index 53dd6f5..93e1afd 100644
--- a/pytest_doctestplus/output_checker.py
+++ b/pytest_doctestplus/output_checker.py
@@ -64,7 +64,7 @@ def __init__(self):
         # floats in the 'want' string may contain ellipses
         want_floats = got_floats + r'(\.{3})?'
 
-        front_sep = r'\s|[*+-,<=(\[]'
+        front_sep = r'\s|[*+\-,<=(\[]'
         back_sep = front_sep + r'|[>j)\]}]'
 
         fbeg = fr'^{got_floats}(?={back_sep}|$)'
diff --git a/tests/test_doctestplus.py b/tests/test_doctestplus.py
index 91542ce..25f3b96 100644
--- a/tests/test_doctestplus.py
+++ b/tests/test_doctestplus.py
@@ -147,6 +147,28 @@ def g():
     reprec.assertoutcome(failed=0, passed=1)
 
 
+def test_float_cmp_complex(testdir):
+    testdir.makeini(
+        """
+        [pytest]
+        doctestplus = enabled
+    """
+    )
+    p = testdir.makepyfile(
+        """
+        def g():
+            '''
+            >>> x = complex(1/3., -2/3.)
+            >>> x    # doctest: +FLOAT_CMP
+            (0.333333-0.666666j)
+            '''
+            pass
+    """
+    )
+    reprec = testdir.inline_run(p, "--doctest-plus")
+    reprec.assertoutcome(failed=0, passed=1)
+
+
 def test_float_cmp_global(testdir):
     testdir.makeini("""
         [pytest]