diff --git a/src/lexer.rs b/src/lexer.rs
index d4d6198..1e8ab4b 100644
--- a/src/lexer.rs
+++ b/src/lexer.rs
@@ -38,6 +38,10 @@ pub enum Token<'a> {
 
 impl<'a> Token<'a> {
     pub fn tokens_to_string(tokens: &[Token]) -> String {
+        if tokens.len() >= 2 && (tokens[0] == Self::Object("struct") || tokens[1] == Self::Object("struct")) {
+            return Self::struct_tokens_to_string(tokens);
+        }
+
         let space_after = [Token::Comma, Token::Asterisk];
         let mut string = String::new();
 
@@ -69,7 +73,7 @@ impl<'a> Token<'a> {
         string
     }
 
-    pub fn struct_tokens_to_string(tokens: &[Token]) -> String {
+    fn struct_tokens_to_string(tokens: &[Token]) -> String {
         let mut string = String::new();
         let mut in_struct = false;
 
@@ -520,6 +524,35 @@ pub fn get_structs<'a>(tokens: &'a Vec<Token>) -> Vec<&'a [Token<'a>]> {
     structs
 }
 
+pub fn get_defines<'a>(tokens: &'a Vec<Token>) -> Vec<&'a [Token<'a>]> {
+    let mut defines = vec![];
+
+    let mut idx: usize = 0;
+
+    while idx < tokens.len() {
+        if tokens[idx] != Token::HashTag {
+            skip_to(tokens, Token::HashTag, &mut idx);
+        }
+        
+        let start_idx = idx;
+
+        if idx + 1 >= tokens.len() || tokens[idx+1] != Token::Object("define") {
+            idx += 2;
+            continue;
+        }
+        idx += 1;
+
+        skip_to(tokens, Token::NewLine, &mut idx);
+        while idx < tokens.len() && tokens[idx-1] == Token::BackSlash {
+            skip_to(tokens, Token::NewLine, &mut idx);
+        }
+
+        defines.push(&tokens[start_idx..idx]);
+    }
+
+    defines
+}
+
 fn struct_len(tokens: &[Token]) -> Option<usize> {
     let mut num_brackets = 0;
     let mut contains_brackets = false;
@@ -552,13 +585,18 @@ fn struct_len(tokens: &[Token]) -> Option<usize> {
     None
 }
 
+/// Updates `idx` to point to the next token specified. If the 
+/// token does not exist, `idx` will be set equal to tokens.len()
 fn skip_to(tokens: &[Token], target: Token, idx: &mut usize) {
     for i in (*idx + 1)..tokens.len() {
         *idx = i;
         if tokens[i] == target {
-            break;
+            return;
         }
     }
+
+    // If the for loop ends, we haven't found it, so set idx appropriatly
+    *idx = tokens.len();
 }
 
 /// Ignores values inside the targets, it just skips to the next token
@@ -573,3 +611,47 @@ fn skip_to_oneof(tokens: &[Token], targets: &[Token], idx: &mut usize) {
         }
     }
 }
+
+
+#[cfg(test)]
+mod lexer_tests {
+    use std::fs;
+
+    use super::*;
+
+    #[test]
+    fn test_get_defines() {
+        let s = fs::read_to_string("tests/lexer-define.c").unwrap();
+        let s = clean_source_code(s);
+        let tokens = tokenize(&s).unwrap();
+
+        let defines = get_defines(&tokens);
+
+        let mut log_dump = "".to_string();
+        for &def in &defines {
+            let x = format!("{:?}\n\n", def);
+            log_dump.push_str(&x);
+        }
+
+        fs::write("tests/lexer-define.log", format!("{}", log_dump)).unwrap();
+
+        assert_eq!(defines.len(), s.split("#define").collect::<Vec<&str>>().len() - 1);
+    }
+
+    #[test]
+    fn test_get_structs() {
+        let s = fs::read_to_string("tests/lexer-struct.c").unwrap();
+        let s = clean_source_code(s);
+        let tokens = tokenize(&s).unwrap();
+
+        let defines = get_structs(&tokens);
+
+        let mut log_dump = "".to_string();
+        for &def in &defines {
+            let x = format!("{:?}\n\n", def);
+            log_dump.push_str(&x);
+        }
+
+        fs::write("tests/lexer-struct.log", format!("{}", log_dump)).unwrap();
+    }
+}
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index fc57450..a9442be 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -20,6 +20,7 @@ use valgrind::VgOutput;
 
 #[tokio::main(flavor = "current_thread")]
 async fn main() {
+
     let cli_args: cli::CliCommand;
     let raw_cli_args = std::env::args().collect::<Vec<String>>();
     if raw_cli_args.len() < 2 {
@@ -96,7 +97,7 @@ async fn main() {
                 process::exit(0);
             }
 
-            if let Err(err) = handle_headers(&config) {
+            if let Err(err) = handle_gen_headers(&config) {
                 println!("An error occured while generating header files:\n{}", err);
                 process::exit(1);
             }
@@ -331,7 +332,7 @@ fn handle_execution(
     Ok(())
 }
 
-fn handle_headers(config: &Config) -> Result<()> {
+fn handle_gen_headers(config: &Config) -> Result<()> {
     let cwd = env::current_dir()?;
     let src_dir = config.get_src_dir();
     let inc_dir = config.get_include_dir();
@@ -357,9 +358,16 @@ fn handle_headers(config: &Config) -> Result<()> {
             code_h = lexer::clean_source_code(code_h);
             let tokens_h = lexer::tokenize(&code_h)?;
 
+            let mut defines_h = lexer::get_defines(&tokens_h);
+            let mut sturcts_h = lexer::get_structs(&tokens_h);
+
             let fn_defs = lexer::get_fn_def(&tokens);
             let includes = lexer::get_includes(&tokens);
-            let structs = lexer::get_structs(&tokens_h);
+            let defines = lexer::get_defines(&tokens);
+            let structs = lexer::get_structs(&tokens);
+
+            defines_h.extend_from_slice(&defines[1..]); // Skip the first definition to skip the #ifndef NAME_H #define NAME_H 
+            sturcts_h.extend_from_slice(&structs);
 
             let mut headers = String::new();
 
@@ -372,8 +380,16 @@ fn handle_headers(config: &Config) -> Result<()> {
                 headers.push('\n');
             }
             headers.push('\n');
-            for &struc in &structs {
-                headers.push_str(&lexer::Token::struct_tokens_to_string(struc).trim());
+
+            for &def in &defines_h {
+                let s = lexer::Token::tokens_to_string(def);
+                headers.push_str(&s);
+                headers.push('\n');
+            }
+            headers.push('\n');
+
+            for &struc in &sturcts_h {
+                headers.push_str(&lexer::Token::tokens_to_string(struc).trim());
                 headers.push_str("\n\n");
             }
             for &func in &fn_defs {
diff --git a/tests/lexer-define.c b/tests/lexer-define.c
new file mode 100644
index 0000000..527e9e3
--- /dev/null
+++ b/tests/lexer-define.c
@@ -0,0 +1,7 @@
+
+#define FOO 982
+
+#define PRINT_HELLO_WORLD() do {         \
+    printf("Hello, ");                   \
+    printf("World!\n");                  \
+} while(0)
\ No newline at end of file
diff --git a/tests/lexer-struct.c b/tests/lexer-struct.c
new file mode 100644
index 0000000..7b24c6f
--- /dev/null
+++ b/tests/lexer-struct.c
@@ -0,0 +1,72 @@
+// Test case 1: Simple struct definition
+struct Point {
+    int x;
+    int y;
+};
+
+// Test case 2: Typedef struct without a tag
+typedef struct {
+    float real;
+    float imag;
+} Complex;
+
+// Test case 3: Typedef struct with a tag
+typedef struct Rectangle {
+    int width;
+    int height;
+} Rectangle;
+
+// Test case 4: Struct with a single member
+struct Circle {
+    float radius;
+};
+
+// Test case 5: Struct with a nested struct definition
+struct Line {
+    // Nested struct definition inside a struct
+    struct Point {
+        int x;
+        int y;
+    } start, end;
+};
+
+// Test case 6: Struct with an anonymous struct member
+struct Node {
+    int value;
+    struct {
+        int left;
+        int right;
+    } children;
+};
+
+// Test case 7: Struct representing a linked list node (self-referential)
+struct List {
+    int data;
+    struct List *next;
+};
+
+// Test case 8: Struct with bit fields
+struct Flags {
+    unsigned int flag1 : 1;
+    unsigned int flag2 : 1;
+};
+
+// Test case 9: Typedef struct with more complex members
+typedef struct Employee {
+    char name[50];
+    int id;
+    float salary;
+} Employee;
+
+// Test case 10: Struct for a binary tree node (self-referential pointers)
+struct TreeNode {
+    int value;
+    struct TreeNode *left;
+    struct TreeNode *right;
+};
+
+// Test case 11: Typedef struct with a different alias
+typedef struct Car {
+    int wheels;
+    float engine_power;
+} Vehicle;