diff --git a/makefile b/makefile
index 50e3f00..7c33a05 100644
--- a/makefile
+++ b/makefile
@@ -11,7 +11,7 @@ $(TARGET): build/parser.o build/lexer.o build/main.o
 build/parser.cpp build/parser.hpp: src/parser.y | build
 	$(BISON) -d -o build/parser.cpp src/parser.y
 
-build/lexer.cpp build/lexer.hpp: src/lexer.l build/parser.hpp | build
+build/lexer.cpp build/lexer.hpp: src/lexer.l build/parser.hpp src/scanner.hpp | build
 	$(FLEX) --header-file=build/lexer.hpp -o build/lexer.cpp src/lexer.l
 
 build/%.o: build/%.cpp
diff --git a/src/lexer.l b/src/lexer.l
index c89a0c2..c2afe7e 100644
--- a/src/lexer.l
+++ b/src/lexer.l
@@ -3,28 +3,7 @@
 %option yyclass="Scanner"
 
 %{
-#include "../build/parser.hpp"
-#include <string>
-
-class Scanner : public yyFlexLexer {
-public:
-    Scanner(std::istream* in) : yyFlexLexer(in) {}
-    
-    int yylex(); 
-
-    int lex(yy::parser::semantic_type* yylval) {
-        this->yylval = yylval;
-        return yylex();
-    }
-    
-private:
-    yy::parser::semantic_type* yylval;
-};
-
-int scanner_lex(yy::parser::semantic_type* yylval) {
-    static Scanner scanner(&std::cin);
-    return scanner.lex(yylval);
-}
+#include "../src/scanner.hpp"
 %}
 
 %%
diff --git a/src/scanner.hpp b/src/scanner.hpp
new file mode 100644
index 0000000..1a84b48
--- /dev/null
+++ b/src/scanner.hpp
@@ -0,0 +1,28 @@
+#pragma once
+#include "../build/parser.hpp"
+#include <string>
+
+class yyFlexLexer;
+
+class Scanner : public yyFlexLexer
+{
+public:
+    Scanner(std::istream *in) : yyFlexLexer(in) {}
+
+    int yylex();
+
+    int lex(yy::parser::semantic_type *yylval)
+    {
+        this->yylval = yylval;
+        return yylex();
+    }
+
+private:
+    yy::parser::semantic_type *yylval;
+};
+
+int scanner_lex(yy::parser::semantic_type *yylval)
+{
+    static Scanner scanner(&std::cin);
+    return scanner.lex(yylval);
+}
\ No newline at end of file