diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9c5ee4d73..a46e8e92a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,9 +4,12 @@ Changelog
 NOTE: isort follows the [semver](https://semver.org/) versioning standard.
 Find out more about isort's release policy [here](https://pycqa.github.io/isort/docs/major_releases/release_policy/).
 
+### 5.5.5 [Hotfix] October 7, 2020
+  - Fixed #1539: isort 5.5.4 introduces syntax error by removing closing paren.
+
 ### 5.5.4 [Hotfix] September 29, 2020
   - Fixed #1507: in rare cases isort changes the content of multiline strings after a yield statement.
-  - Fixed #1505: Support case where known_SECTION points to a section not listed in sections. 
+  - Fixed #1505: Support case where known_SECTION points to a section not listed in sections.
 
 ### 5.5.3 [Hotfix] September 20, 2020
   - Fixed #1488: in rare cases isort can mangle `yield from` or `raise from` statements.
diff --git a/isort/_version.py b/isort/_version.py
index e82c92eb4..3a831202b 100644
--- a/isort/_version.py
+++ b/isort/_version.py
@@ -1 +1 @@
-__version__ = "5.5.4"
+__version__ = "5.5.5"
diff --git a/isort/core.py b/isort/core.py
index 696e5d751..558fc2adc 100644
--- a/isort/core.py
+++ b/isort/core.py
@@ -153,6 +153,7 @@ def process(
                     in_top_comment = False
                     first_comment_index_end = index - 1
 
+            was_in_quote = bool(in_quote)
             if (not stripped_line.startswith("#") or in_quote) and '"' in line or "'" in line:
                 char_index = 0
                 if first_comment_index_start == -1 and (
@@ -178,8 +179,8 @@ def process(
                         break
                     char_index += 1
 
-            not_imports = bool(in_quote) or in_top_comment or isort_off
-            if not (in_quote or in_top_comment):
+            not_imports = bool(in_quote) or was_in_quote or in_top_comment or isort_off
+            if not (in_quote or was_in_quote or in_top_comment):
                 if isort_off:
                     if stripped_line == "# isort: on":
                         isort_off = False
diff --git a/pyproject.toml b/pyproject.toml
index 75fb08633..e9b1fdc49 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -3,7 +3,7 @@ line-length = 100
 
 [tool.poetry]
 name = "isort"
-version = "5.5.4"
+version = "5.5.5"
 description = "A Python utility / library to sort Python imports."
 authors = ["Timothy Crosley <timothy.crosley@gmail.com>"]
 license = "MIT"
diff --git a/tests/unit/test_regressions.py b/tests/unit/test_regressions.py
index 78888c409..09d4302d1 100644
--- a/tests/unit/test_regressions.py
+++ b/tests/unit/test_regressions.py
@@ -1121,3 +1121,52 @@ def d():
 ''',
         show_diff=True,
     )
+
+
+def test_isort_shouldnt_introduce_syntax_error_issue_1539():
+    """isort should NEVER introduce syntax errors.
+    In 5.5.4 some strings that contained a line starting with from could lead to no empty paren.
+    See: https://github.com/PyCQA/isort/issues/1539.
+    """
+    assert isort.check_code(
+        '''"""Foobar
+    from {}""".format(
+    "bar",
+)
+''',
+        show_diff=True,
+    )
+    assert isort.check_code(
+        '''"""Foobar
+    import {}""".format(
+    "bar",
+)
+''',
+        show_diff=True,
+    )
+    assert (
+        isort.code(
+            '''"""Foobar
+    from {}"""
+    from a import b, a
+''',
+        )
+        == '''"""Foobar
+    from {}"""
+    from a import a, b
+'''
+    )
+    assert (
+        isort.code(
+            '''"""Foobar
+    from {}"""
+    import b
+    import a
+''',
+        )
+        == '''"""Foobar
+    from {}"""
+    import a
+    import b
+'''
+    )