diff --git a/src/libclang/preprocessor.cpp b/src/libclang/preprocessor.cpp
index 7459933..0630979 100644
--- a/src/libclang/preprocessor.cpp
+++ b/src/libclang/preprocessor.cpp
@@ -198,8 +198,11 @@ namespace
 
         void set_line(unsigned line)
         {
-            *result_ += "#line " + std::to_string(line) + "\n";
-            cur_line_ = line;
+            if (cur_line_ != line)
+            {
+                *result_ += "#line " + std::to_string(line) + "\n";
+                cur_line_ = line;
+            }
         }
 
         void write_str(std::string str)