diff --git a/.dir-locals.el b/.dir-locals.el
index 39bb4e6..0ee656d 100644
--- a/.dir-locals.el
+++ b/.dir-locals.el
@@ -7,7 +7,7 @@
                    (define-minor-mode context-mode
                      "A temporary minor mode to be activated only specific to a buffer."
                      nil
-                     :lighter " Context"
+                     :lighter " [f2]-Context"
                      context-mode-map)
                    (context-mode 1)
 
diff --git a/build.bat b/build.bat
index 3799856..51e924a 100644
--- a/build.bat
+++ b/build.bat
@@ -22,5 +22,4 @@ if %errorlevel% == 0 (
 )
 
 popd
-rem rd build /S /Q
 popd
diff --git a/build/libucrtd.lib b/build/libucrtd.lib
new file mode 100644
index 0000000..4607828
Binary files /dev/null and b/build/libucrtd.lib differ
diff --git a/build_clang.bat b/build_clang.bat
new file mode 100644
index 0000000..d746f93
--- /dev/null
+++ b/build_clang.bat
@@ -0,0 +1,25 @@
+@echo off
+@setlocal
+pushd %~dp0
+
+set exeName=slime.exe
+set binDir=bin
+
+mkdir build 2>nul
+pushd build
+
+taskkill /F /IM %exeName% > NUL 2> NUL
+
+echo ---------- Compiling ----------
+call timecmd clang++ -std=c++17 ../src/main.cpp -o %exeName% -D_DEBUG libucrtd.lib
+
+if %errorlevel% == 0 (
+   echo.
+   echo Done
+) else (
+  echo.
+  echo Fuckin' ell
+)
+
+popd
+popd
diff --git a/src/built_ins.cpp b/src/built_ins.cpp
index 5774aa1..396859b 100644
--- a/src/built_ins.cpp
+++ b/src/built_ins.cpp
@@ -270,7 +270,7 @@ proc built_in_exponentiate(Lisp_Object* arguments, Environment* env) -> Lisp_Obj
 }
 
 
-proc built_in_load(char* file_name, Environment* env) -> Lisp_Object* {
+proc built_in_load(const char* file_name, Environment* env) -> Lisp_Object* {
     char* file_content = read_entire_file(file_name);
     if (file_content) {
         Lisp_Object* result = Memory::create_lisp_object_nil();
@@ -300,7 +300,7 @@ proc load_built_ins_into_environment(Environment* env) -> void {
         return nullptr;                                         \
     }
 
-    proc defun = [&](char* name, std::function<Lisp_Object*(Lisp_Object*, Environment*)> fun) {
+    proc defun = [&](const char* name, std::function<Lisp_Object*(Lisp_Object*, Environment*)> fun) {
         define_symbol(
             Memory::create_lisp_object_symbol(name),
             Memory::create_lisp_object_cfunction(fun),
@@ -970,9 +970,7 @@ proc load_built_ins_into_environment(Environment* env) -> void {
         });
     defun("break", cLambda {
             print_environment(env);
-            if_debug {
-                __debugbreak();
-            }
+            debug_break();
             return Memory::create_lisp_object_nil();
         });
     defun("memstat", cLambda {
diff --git a/src/defines.cpp b/src/defines.cpp
index c97314f..4230ed2 100644
--- a/src/defines.cpp
+++ b/src/defines.cpp
@@ -9,15 +9,20 @@ constexpr bool is_debug_build = false;
 
 #define if_debug if constexpr (is_debug_build)
 
+// #ifdef _MSC_VER
+# define debug_break() if_debug __debugbreak()
+// #else
+// # define debug_break() if_debug __builtin_trap()
+// #endif
+
 #define assert(cond)                                                    \
     if_debug {                                                          \
         if (!cond) {                                                    \
             printf("Assertion failed: %s %d", __FILE__, __LINE__);      \
-            __debugbreak();                                             \
+            debug_break();                                              \
         }                                                               \
     } else {}                                                           \
 
-
 #define concat_( a, b) a##b
 #define label(prefix, lnum) concat_(prefix,lnum)
 #define try                                     \
diff --git a/src/error.cpp b/src/error.cpp
index 3dfdcaf..5141eb3 100644
--- a/src/error.cpp
+++ b/src/error.cpp
@@ -10,14 +10,14 @@ proc delete_error() -> void {
 proc create_error(Error_Type type, Source_Code_Location* location) -> void {
     delete_error();
     if_debug {
-        __debugbreak();
+        debug_break();
     }
     error = new(Error);
     error->type = type;
     error->location = location;
 }
 
-proc Error_Type_to_string(Error_Type type) -> char* {
+proc Error_Type_to_string(Error_Type type) -> const char* {
     switch (type) {
     case Error_Type::Ill_Formed_Arguments:      return "Evaluation-error: Ill formed arguments";
     case Error_Type::Ill_Formed_Lambda_List:    return "Evaluation-error: Ill formed lambda list";
diff --git a/src/forward_decls.cpp b/src/forward_decls.cpp
index fc1893d..f3b0e61 100644
--- a/src/forward_decls.cpp
+++ b/src/forward_decls.cpp
@@ -1,7 +1,7 @@
-proc print_environment(Environment* env) -> void;
-proc eval_arguments(Lisp_Object* arguments, Environment* env, int *out_arguments_length) -> Lisp_Object*;
+proc print_environment(Environment*) -> void;
+proc eval_arguments(Lisp_Object*, Environment*, int*) -> Lisp_Object*;
 proc eval_expr(Lisp_Object*, Environment*) -> Lisp_Object*;
-proc is_truthy (Lisp_Object* expression, Environment* env) -> bool;
+proc is_truthy (Lisp_Object*, Environment*) -> bool;
 proc list_length(Lisp_Object*) -> int;
 proc load_built_ins_into_environment(Environment*) -> void;
 proc parse_argument_list(Lisp_Object*, Function*) -> void;
diff --git a/src/io.cpp b/src/io.cpp
index 2321f39..02a917c 100644
--- a/src/io.cpp
+++ b/src/io.cpp
@@ -1,4 +1,4 @@
-proc string_equal(char input[],char check[]) -> bool {
+proc string_equal(const char input[], const char check[]) -> bool {
     int i;
     for(i = 0; input[i] != '\0' || check[i] != '\0'; i++) {
         if(input[i] != check[i]) {
@@ -67,7 +67,7 @@ proc unescape_string(char* in) -> bool {
     return true;
 }
 
-proc read_entire_file (char* filename) -> char* {
+proc read_entire_file (const char* filename) -> char* {
     char *fileContent = nullptr;
     FILE *fp = fopen(filename, "r");
     if (fp) {
@@ -132,7 +132,7 @@ proc read_expression() -> char* {
             linep = linen;
         }
 
-        *line++;
+        line++;
         if((*line = (char)c) == '(')
             ++nesting;
         else if((*line = (char)c) == ')')
@@ -144,6 +144,7 @@ proc read_expression() -> char* {
     (*line)--; // we dont want the \n actually
     *line = '\0';
     // BUG(Felix): Why do we have to add 1 here?
+
     return linep + 1;
 }
 
@@ -174,7 +175,7 @@ proc read_line() -> char* {
             linep = linen;
         }
 
-        *line++;
+        line++;
         if((*line = (char)c) == '(')
             ++nesting;
         else if((*line = (char)c) == ')')
@@ -196,7 +197,7 @@ proc log_message(Log_Level type, char* message) -> void {
     if (type > log_level)
         return;
 
-    char* prefix;
+    const char* prefix;
     switch (type) {
     case Log_Level::Critical: prefix = "CRITICAL"; break;
     case Log_Level::Warning:  prefix = "WARNING";  break;
diff --git a/src/lisp_object.cpp b/src/lisp_object.cpp
index a95091a..0876ce3 100644
--- a/src/lisp_object.cpp
+++ b/src/lisp_object.cpp
@@ -1,4 +1,4 @@
-proc create_source_code_location(char* file, int line, int col) -> Source_Code_Location* {
+proc create_source_code_location(const char* file, int line, int col) -> Source_Code_Location* {
     if (!file)
         return nullptr;
 
@@ -9,7 +9,7 @@ proc create_source_code_location(char* file, int line, int col) -> Source_Code_L
     return ret;
 }
 
-proc Lisp_Object_Type_to_string(Lisp_Object_Type type) -> char* {
+proc Lisp_Object_Type_to_string(Lisp_Object_Type type) -> const char* {
     switch (type) {
     case(Lisp_Object_Type::Nil):       return "nil";
     case(Lisp_Object_Type::T):         return "t";
diff --git a/src/main.cpp b/src/main.cpp
index cedb515..4090244 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -9,6 +9,6 @@ int main(int argc, char* argv[]) {
         }
     } else {
         run_all_tests();
-        return interprete_stdin();
+        interprete_stdin();
     }
 }
diff --git a/src/memory.cpp b/src/memory.cpp
index 0c78623..0a4447a 100644
--- a/src/memory.cpp
+++ b/src/memory.cpp
@@ -70,19 +70,19 @@ namespace Memory {
         return node;
     }
 
-    proc create_lisp_object_symbol(char* identifier) -> Lisp_Object* {
+    proc create_lisp_object_symbol(const char* identifier) -> Lisp_Object* {
         Lisp_Object* node = create_lisp_object();
         node->type = Lisp_Object_Type::Symbol;
         node->value.symbol = new(Symbol);
-        node->value.symbol->identifier = identifier;
+        node->value.symbol->identifier = (char*) identifier;
         return node;
     }
 
-    proc create_lisp_object_keyword(char* keyword) -> Lisp_Object* {
+    proc create_lisp_object_keyword(const char* keyword) -> Lisp_Object* {
         Lisp_Object* node = create_lisp_object();
         node->type = Lisp_Object_Type::Keyword;
         node->value.keyword = new(Keyword);
-        node->value.keyword->identifier = keyword;
+        node->value.keyword->identifier = (char*) keyword;
         return node;
     }
 
diff --git a/src/parse.cpp b/src/parse.cpp
index ad6654d..4deeb31 100644
--- a/src/parse.cpp
+++ b/src/parse.cpp
@@ -1,12 +1,12 @@
 namespace Parser {
 
-#define inject_scl(_ret)                                        \
-    ret->sourceCodeLocation = new(Source_Code_Location);        \
-    ret->sourceCodeLocation->file   = parser_file;              \
-    ret->sourceCodeLocation->line   = parser_line;              \
-    ret->sourceCodeLocation->column = parser_col
+#define inject_scl(_ret)                                         \
+    _ret->sourceCodeLocation = new(Source_Code_Location);        \
+    _ret->sourceCodeLocation->file   = parser_file;              \
+    _ret->sourceCodeLocation->line   = parser_line;              \
+    _ret->sourceCodeLocation->column = parser_col
 
-    char* parser_file;
+    const char* parser_file;
     int parser_line;
     int parser_col;
 
@@ -466,8 +466,8 @@ namespace Parser {
         return nullptr;
     }
 
-    void write_expanded_file(char* file_name, Lisp_Object_Array_List* program) {
-        char* ext = ".expanded";
+    void write_expanded_file(const char* file_name, Lisp_Object_Array_List* program) {
+        const char* ext = ".expanded";
         char* newName = (char*)calloc(4 + strlen(file_name), sizeof(char));
         strcpy(newName, file_name);
         strcat(newName, ext);
@@ -489,9 +489,9 @@ namespace Parser {
         fclose(f);
     }
 
-    Lisp_Object_Array_List* parse_program(char* file_name, char* text) {
+    Lisp_Object_Array_List* parse_program(const char* file_name, char* text) {
         parser_file = (char*)malloc(strlen(file_name) * sizeof(char) + 1);
-        strcpy(parser_file, file_name);
+        strcpy((char *)parser_file, file_name);
         parser_line = 1;
         parser_col = 0;
 
diff --git a/src/structs.cpp b/src/structs.cpp
index bff4a49..1327612 100644
--- a/src/structs.cpp
+++ b/src/structs.cpp
@@ -50,7 +50,7 @@ enum struct Log_Level {
 };
 
 struct Source_Code_Location {
-    char* file;
+    const char* file;
     int line;
     int column;
 };
@@ -68,8 +68,8 @@ struct Number {
 };
 
 struct String {
-    char* value;
     int length;
+    char* value;
 };
 
 struct Pair {