diff --git a/src/Lexer.cpp b/src/Lexer.cpp
index e32dd09..c571f8f 100644
--- a/src/Lexer.cpp
+++ b/src/Lexer.cpp
@@ -7,7 +7,7 @@
 #define IDENTIFIERS "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWYZ_0123456789"
 #define DIGITS "0123456789"
 
-Lexer::Lexer(const std::string& fname) : location(1, 0, fname), index(-1), previous_location(1, 0, fname)
+Lexer::Lexer(const std::string& fname) : location(1, 0, fname), previous_location(1, 0, fname), index(-1)
 {
 }
 
@@ -17,10 +17,10 @@ Lexer::~Lexer()
 
 int Lexer::advance()
 {
-    previous_location = location;
+    previous_location = Location{ location };
     ++index;
     location.advance();
-    if (index >= current_lexed_text.size()) return 0;
+    if (index >= (ssize_t)current_lexed_text.size()) return 0;
     current_char = current_lexed_text[index];
     location.pos_from_char(current_char);
     if (current_char == '\n')
@@ -46,10 +46,10 @@ int Lexer::rewind()
 
 std::string Lexer::recalculate_current_line(const std::string& text)
 {
-    int idx = index;
+    ssize_t idx = index;
     std::string final_str;
     ++idx;
-    while (idx != text.size() && text[idx] != '\n')
+    while (idx != (ssize_t)text.size() && text[idx] != '\n')
     {
         final_str += text[idx];
         ++idx;
@@ -106,7 +106,7 @@ TokenStream Lexer::lex(const std::string& text)
             switch (current_char)
             {
             case '/':
-                if (index + 1 != current_lexed_text.size())
+                if (index + 1 != (ssize_t)current_lexed_text.size())
                 {
                     if (current_lexed_text[index + 1] == '/')
                     {
@@ -172,7 +172,7 @@ TokenStream Lexer::lex(const std::string& text)
                 break;
             case '\377':
                 result.push_back(Token(TT_EOF, location));
-                return std::move(result);
+                return result;
             default:
                 Error::throw_error(location, current_line_text, "unknown character");
             }
@@ -180,7 +180,7 @@ TokenStream Lexer::lex(const std::string& text)
 
     result.push_back(Token(TT_EOF, location));
 
-    return std::move(result);
+    return result;
 }
 
 Token Lexer::create_identifier()
@@ -303,7 +303,7 @@ Token Lexer::create_string()
         }
         if (current_char == '\\')
         {
-            if (index + 1 == current_lexed_text.size())
+            if (index + 1 == (ssize_t)current_lexed_text.size())
             {
                 Error::throw_error(location, current_line_text, "unfinished escape sequence");
             }
diff --git a/src/Lexer.h b/src/Lexer.h
index 32848ff..5e44844 100644
--- a/src/Lexer.h
+++ b/src/Lexer.h
@@ -19,7 +19,7 @@ class Lexer
     int advance();
     int rewind();
     char current_char;
-    int index;
+    ssize_t index;
 
     Lexer(const std::string& filename);
 
diff --git a/src/Parser.cpp b/src/Parser.cpp
index ab61b63..a019e4d 100644
--- a/src/Parser.cpp
+++ b/src/Parser.cpp
@@ -37,7 +37,7 @@ std::shared_ptr<ProgramNode> Parser::parse()
 int Parser::advance()
 {
     ++index;
-    if (index < tokens.size())
+    if (index < (ssize_t)tokens.size())
     {
         current_token = &tokens[index];
     }
@@ -136,7 +136,7 @@ Result<TopLevelNode> Parser::function()
         {
             proto.returnType = m_type_map.at(current_token->string_value.value());
         }
-        catch (std::out_of_range)
+        catch (const std::out_of_range&)
         {
             return Err<TopLevelNode>("Expected type name", current_token);
         }
diff --git a/src/Parser.h b/src/Parser.h
index 5b8acd2..c71db3c 100644
--- a/src/Parser.h
+++ b/src/Parser.h
@@ -14,7 +14,7 @@ class Parser
   private:
     Parser(const TokenStream& tokens);
     TokenStream tokens;
-    int index = -1;
+    ssize_t index = -1;
     int advance();
     Token* current_token;