diff --git a/src/json.hpp b/src/json.hpp
index e71ffc4a290ffdfeaf12df19abb8d47a79c19625..915a60f441feb13af72c30f2a051a92119bc88a6 100644
--- a/src/json.hpp
+++ b/src/json.hpp
@@ -8743,7 +8743,10 @@ basic_json_parser_66:
                 // append n characters to make sure that there is sufficient
                 // space between m_cursor and m_limit
                 m_line_buffer.append(1, '\x00');
-                m_line_buffer.append(n - 1, '\x01');
+                if (n > 0)
+                {
+                    m_line_buffer.append(n - 1, '\x01');
+                }
             }
             else
             {
diff --git a/src/json.hpp.re2c b/src/json.hpp.re2c
index 9eccc144f037f85788f613f0eeb4da6e6c7dc770..9b21c828ef4fe1afa68a9b909df2afde973a6080 100644
--- a/src/json.hpp.re2c
+++ b/src/json.hpp.re2c
@@ -7892,7 +7892,10 @@ class basic_json
                 // append n characters to make sure that there is sufficient
                 // space between m_cursor and m_limit
                 m_line_buffer.append(1, '\x00');
-                m_line_buffer.append(n - 1, '\x01');
+                if (n > 0)
+                {
+                    m_line_buffer.append(n - 1, '\x01');
+                }
             }
             else
             {