diff --git a/src/lib.rs b/src/lib.rs
index c288fa4..2ae377b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -15,13 +15,19 @@ fn parse_line<'a>(line: &'a str) -> LineType<'a> {
         let filelist_name = line.trim_start_matches("-f ");
         return LineType::Filelist(filelist_name);
     } else if line.starts_with("+define+") {
-        let defines = line.trim_start_matches("+define+");
+        // remove +define+ from start and "+" from end
+        let defines = line.trim_start_matches("+define+").trim_end_matches("+");
         let mut define_map = HashMap::new();
         for define in defines.split("+") {
             let split: Vec<&str> = define.splitn(2, "=").collect();
             define_map.insert(split[0], split[1]);
         }
         return LineType::Define(define_map);
+    } else if line.starts_with("+incdir+") {
+        // remove +incdir+ from start and "+" from end
+        let incdirs = line.trim_start_matches("+incdir+").trim_end_matches("+");
+        let incdir_vec: Vec<&str> = incdirs.split("+").collect();
+        return LineType::IncDir(incdir_vec);
     } else {
         return LineType::Unknown;
     }
@@ -33,17 +39,40 @@ mod test {
 
     #[test]
     fn parse_line_filelist() {
-        let line = "-f sample/files.f";
+        let line = "-f sample/files.f\n";
         assert_eq!(parse_line(line), LineType::Filelist("sample/files.f"));
     }
 
     #[test]
-    fn parse_line_define() {
-        let line = "+define+CONST1=const1+CONST2=const2+CONST3=const3=1";
+    fn parse_line_define_single() {
+        let line = "+define+CONST1=const1=23\n";
+        let mut define_map = HashMap::new();
+        define_map.insert("CONST1", "const1=23");
+        assert_eq!(parse_line(line), LineType::Define(define_map));
+    }
+
+    #[test]
+    fn parse_line_define_multiple() {
+        let line = "+define+CONST1=const1+CONST2=const2+CONST3=const3=1+\n";
         let mut define_map = HashMap::new();
         define_map.insert("CONST1", "const1");
         define_map.insert("CONST2", "const2");
         define_map.insert("CONST3", "const3=1");
         assert_eq!(parse_line(line), LineType::Define(define_map));
     }
+
+    #[test]
+    fn parse_line_incdir_single() {
+        let line = "+incdir+../sample_dir1/sample_dir2\n";
+        let incdir_vec = vec!["../sample_dir1/sample_dir2"];
+        assert_eq!(parse_line(line), LineType::IncDir(incdir_vec));
+    }
+
+    #[test]
+    fn parse_line_incdir_multiple() {
+        let line = "+incdir+../sample_dir1/sample_dir2+../sample_dir2/sample_dir3+sample_dir4/sample_dir5+\n";
+        let incdir_vec = vec!["../sample_dir1/sample_dir2", "../sample_dir2/sample_dir3", 
+            "sample_dir4/sample_dir5"];
+        assert_eq!(parse_line(line), LineType::IncDir(incdir_vec));
+    }
 }
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