diff --git a/src/lexer.py b/src/lexer.py
index 0eb0dad..8803e70 100644
--- a/src/lexer.py
+++ b/src/lexer.py
@@ -138,7 +138,7 @@ def t_MLSTR(t):
 
 
 def t_STR(t):
-    r"(\"(?:[^\"\\]|\\.)*\")|(\'[^\']*\')"
+    r"(\"(?:[^\"\\]|\\.)*\")|(\'[^\'\n]*\')"
     t.value = t.value.strip("\"'")
     return t