diff --git a/fortls/langserver.py b/fortls/langserver.py
index bb9b01bf..54de9d44 100644
--- a/fortls/langserver.py
+++ b/fortls/langserver.py
@@ -882,7 +882,7 @@ def get_all_references(self, def_obj, type_mem, file_obj=None):
         # Search through all files
         def_name = def_obj.name.lower()
         def_fqsn = def_obj.FQSN
-        NAME_REGEX = re.compile(fr"(?:\W|^)({def_name})(?:\W|$)", re.I)
+        NAME_REGEX = re.compile(rf"(?:\W|^)({def_name})(?:\W|$)", re.I)
         if file_obj is None:
             file_set = self.workspace.items()
         else:
diff --git a/fortls/parse_fortran.py b/fortls/parse_fortran.py
index 044eee83..5e463dfe 100644
--- a/fortls/parse_fortran.py
+++ b/fortls/parse_fortran.py
@@ -1381,7 +1381,7 @@ def replace_vars(line: str):
         for def_tmp, value in defs_tmp.items():
             def_regex = def_regexes.get(def_tmp)
             if def_regex is None:
-                def_regex = re.compile(fr"\b{def_tmp}\b")
+                def_regex = re.compile(rf"\b{def_tmp}\b")
                 def_regexes[def_tmp] = def_regex
             line_new, nsubs = def_regex.subn(value, line)
             if nsubs > 0:
diff --git a/fortls/regex_patterns.py b/fortls/regex_patterns.py
index 2abe594e..10df02d1 100644
--- a/fortls/regex_patterns.py
+++ b/fortls/regex_patterns.py
@@ -157,4 +157,4 @@ def src_file_exts(input_exts: list[str] = []) -> Pattern[str]:
             FORTRAN_FILE_EXTS.append(e.replace(".", ""))
     # Cast into a set to ensure uniqueness of extensions & sort for consistency
     # Create a regular expression from this
-    return re.compile(fr"\.({'|'.join(sorted(set(FORTRAN_FILE_EXTS)))})?$")
+    return re.compile(rf"\.({'|'.join(sorted(set(FORTRAN_FILE_EXTS)))})?$")