diff --git a/python/mp_code_expressions.py b/python/mp_code_expressions.py
index dfa0380415b06c902a68ed3cf118733e9c811768..5258756d72150391c7619e62bc9f4bcac3fbd53c 100644
--- a/python/mp_code_expressions.py
+++ b/python/mp_code_expressions.py
@@ -42,24 +42,24 @@ MP_META_SYMBOL_SET = set(MP_META_SYMBOLS.split('|')) # match excludes $$ prefix
 MP_META_SYMBOL_EXPRESSION = QRegularExpression(r'\$\$(%s)'%MP_META_SYMBOLS)
 
 # operators, any of: -+*=<>!(){}|
-OPERATOR_EXPRESSION = QRegularExpression("[-+\/*=<>!\(\)\{\}\|]+")
+OPERATOR_EXPRESSION = QRegularExpression(r"[-+*=<>!(){}|]")
 
 # numbers
-NUMBER_EXPRESSION = QRegularExpression(r'[+-]?[0-9]+(?:\.[0-9]+)?(?:[eE][+-]?[0-9]+)?')
+NUMBER_EXPRESSION = QRegularExpression(r'[0-9]+(?:\.[0-9]+)?(?:[eE][+-]?[0-9]+)?')
 
 # variables
-VARIABLE_EXPRESSION = QRegularExpression("(<.*>)?\$([a-z][a-z0-9_]*)")
+VARIABLE_EXPRESSION = QRegularExpression(r"(<.*>)?\$([a-z][a-z0-9_]*)")
 
 # Double-quoted string, possibly containing escape sequences
 QUOTED_TEXT_EXPRESSION = QRegularExpression(r'"[^"\\]*(\\.[^"\\]*)*"')
 
 # brace, bracket IF, DO
-PAREN_EXPRESSION = QRegularExpression("[\(\)]")   # "(" or ")"
-BRACE_EXPRESSION = QRegularExpression("[\{\}]")   # "{" or "}"
-BRACKET_EXPRESSION = QRegularExpression("[\[\]]")   # "[" or "]"
-IF_EXPRESSION = QRegularExpression("\\b(IF|FI)\\b") # IF or FI
-DO_EXPRESSION = QRegularExpression("\\b(DO|OD)\\b") # DO or OD
+PAREN_EXPRESSION = QRegularExpression(r"[()]")   # "(" or ")"
+BRACE_EXPRESSION = QRegularExpression(r"[{}]")   # "{" or "}"
+BRACKET_EXPRESSION = QRegularExpression(r"[][]")   # "[" or "]"
+IF_EXPRESSION = QRegularExpression(r"\b(IF|FI)\b") # IF or FI
+DO_EXPRESSION = QRegularExpression(r"\b(DO|OD)\b") # DO or OD
 
 # leading whitespace used for auto-indent
-LEADING_WHITESPACE_EXPRESSION = QRegularExpression("^\s*")
+LEADING_WHITESPACE_EXPRESSION = QRegularExpression(r"^\s*")