diff --git a/src/test/file_navigation.rs b/src/test/file_navigation.rs
new file mode 100644
index 00000000..80b8e618
--- /dev/null
+++ b/src/test/file_navigation.rs
@@ -0,0 +1,104 @@
+use crate::*;
+
+
+#[test]
+fn test_file_navigation()
+{
+    test("main.asm", "", Err(()));
+    test("main.asm", ".", Err(()));
+    test("main.asm", "sibling.asm", Ok("sibling.asm"));
+    test("main.asm", "./sibling.asm", Ok("sibling.asm"));
+    test("main.asm", "folder/inner.asm", Ok("folder/inner.asm"));
+    test("main.asm", "./folder/inner.asm", Ok("folder/inner.asm"));
+    test("main.asm", "..", Err(()));
+    test("main.asm", "../outer.asm", Err(()));
+    
+    test("./main.asm", "", Err(()));
+    test("./main.asm", ".", Err(()));
+    test("./main.asm", "sibling.asm", Ok("./sibling.asm"));
+    test("./main.asm", "./sibling.asm", Ok("./sibling.asm"));
+    test("./main.asm", "folder/inner.asm", Ok("./folder/inner.asm"));
+    test("./main.asm", "./folder/inner.asm", Ok("./folder/inner.asm"));
+    test("./main.asm", "..", Err(()));
+    test("./main.asm", "../outer.asm", Ok("outer.asm"));
+
+    test("/main.asm", "", Err(()));
+    test("/main.asm", ".", Err(()));
+    test("/main.asm", "sibling.asm", Ok("/sibling.asm"));
+    test("/main.asm", "./sibling.asm", Ok("/sibling.asm"));
+    test("/main.asm", "folder/inner.asm", Ok("/folder/inner.asm"));
+    test("/main.asm", "./folder/inner.asm", Ok("/folder/inner.asm"));
+    test("/main.asm", "..", Err(()));
+    test("/main.asm", "../outer.asm", Ok("outer.asm"));
+
+    test("C:/main.asm", "", Err(()));
+    test("C:/main.asm", ".", Err(()));
+    test("C:/main.asm", "sibling.asm", Ok("C:/sibling.asm"));
+    test("C:/main.asm", "./sibling.asm", Ok("C:/sibling.asm"));
+    test("C:/main.asm", "folder/inner.asm", Ok("C:/folder/inner.asm"));
+    test("C:/main.asm", "./folder/inner.asm", Ok("C:/folder/inner.asm"));
+    test("C:/main.asm", "..", Err(()));
+    test("C:/main.asm", "../outer.asm", Ok("outer.asm"));
+
+    test("folder/inner.asm", "", Err(()));
+    test("folder/inner.asm", ".", Err(()));
+    test("folder/inner.asm", "sibling.asm", Ok("folder/sibling.asm"));
+    test("folder/inner.asm", "./sibling.asm", Ok("folder/sibling.asm"));
+    test("folder/inner.asm", "folder/inner.asm", Ok("folder/folder/inner.asm"));
+    test("folder/inner.asm", "./folder/inner.asm", Ok("folder/folder/inner.asm"));
+    test("folder/inner.asm", "..", Err(()));
+    test("folder/inner.asm", "../outer.asm", Ok("outer.asm"));
+    
+    test("./folder/inner.asm", "", Err(()));
+    test("./folder/inner.asm", ".", Err(()));
+    test("./folder/inner.asm", "sibling.asm", Ok("./folder/sibling.asm"));
+    test("./folder/inner.asm", "./sibling.asm", Ok("./folder/sibling.asm"));
+    test("./folder/inner.asm", "folder/inner.asm", Ok("./folder/folder/inner.asm"));
+    test("./folder/inner.asm", "./folder/inner.asm", Ok("./folder/folder/inner.asm"));
+    test("./folder/inner.asm", "..", Err(()));
+    test("./folder/inner.asm", "../outer.asm", Ok("./outer.asm"));
+    test("./folder/inner.asm", "../../outer.asm", Ok("outer.asm"));
+    
+    test("/folder/inner.asm", "", Err(()));
+    test("/folder/inner.asm", ".", Err(()));
+    test("/folder/inner.asm", "sibling.asm", Ok("/folder/sibling.asm"));
+    test("/folder/inner.asm", "./sibling.asm", Ok("/folder/sibling.asm"));
+    test("/folder/inner.asm", "folder/inner.asm", Ok("/folder/folder/inner.asm"));
+    test("/folder/inner.asm", "./folder/inner.asm", Ok("/folder/folder/inner.asm"));
+    test("/folder/inner.asm", "..", Err(()));
+    test("/folder/inner.asm", "../outer.asm", Ok("/outer.asm"));
+    test("/folder/inner.asm", "../../outer.asm", Ok("outer.asm"));
+    
+    test("C:/folder/inner.asm", "", Err(()));
+    test("C:/folder/inner.asm", ".", Err(()));
+    test("C:/folder/inner.asm", "sibling.asm", Ok("C:/folder/sibling.asm"));
+    test("C:/folder/inner.asm", "./sibling.asm", Ok("C:/folder/sibling.asm"));
+    test("C:/folder/inner.asm", "folder/inner.asm", Ok("C:/folder/folder/inner.asm"));
+    test("C:/folder/inner.asm", "./folder/inner.asm", Ok("C:/folder/folder/inner.asm"));
+    test("C:/folder/inner.asm", "..", Ok("C:"));
+    test("C:/folder/inner.asm", "../outer.asm", Ok("C:/outer.asm"));
+    test("C:/folder/inner.asm", "../../outer.asm", Ok("outer.asm"));
+    
+    test("folder/subfolder/inner.asm", "", Err(()));
+    test("folder/subfolder/inner.asm", ".", Err(()));
+    test("folder/subfolder/inner.asm", "sibling.asm", Ok("folder/subfolder/sibling.asm"));
+    test("folder/subfolder/inner.asm", "./sibling.asm", Ok("folder/subfolder/sibling.asm"));
+    test("folder/subfolder/inner.asm", "folder/inner.asm", Ok("folder/subfolder/folder/inner.asm"));
+    test("folder/subfolder/inner.asm", "./folder/inner.asm", Ok("folder/subfolder/folder/inner.asm"));
+    test("folder/subfolder/inner.asm", "..", Ok("folder"));
+    test("folder/subfolder/inner.asm", "../outer.asm", Ok("folder/outer.asm"));
+    test("folder/subfolder/inner.asm", "../../outer.asm", Ok("outer.asm"));
+    test("folder/subfolder/inner.asm", "../folder/outer.asm", Ok("folder/folder/outer.asm"));
+}
+
+
+fn test(base: &str, relative: &str, expected: Result<&str, ()>)
+{
+    let mut report = diagn::Report::new();
+    let span = diagn::Span::new_dummy();
+
+    let result = util::filename_navigate(
+        &mut report, span, base, relative);
+
+    assert_eq!(result.as_deref(), expected.as_deref());
+}
\ No newline at end of file
diff --git a/src/test/mod.rs b/src/test/mod.rs
index 45856492..40053988 100644
--- a/src/test/mod.rs
+++ b/src/test/mod.rs
@@ -5,6 +5,7 @@ mod examples;
 mod excerpt;
 mod expr;
 mod file;
+mod file_navigation;
 mod lib;
 
 
diff --git a/src/util/filename.rs b/src/util/file_navigation.rs
similarity index 72%
rename from src/util/filename.rs
rename to src/util/file_navigation.rs
index e7360a7e..5310c637 100644
--- a/src/util/filename.rs
+++ b/src/util/file_navigation.rs
@@ -12,7 +12,7 @@ pub fn is_std_path(
 }
 
 
-pub fn filename_validate(
+pub fn filename_validate_relative(
 	report: &mut diagn::Report,
 	span: diagn::Span,
 	filename: &str)
@@ -48,18 +48,18 @@ pub fn filename_navigate(
 	report: &mut diagn::Report,
 	span: diagn::Span,
 	current: &str,
-	nav: &str)
+	relative: &str)
 	-> Result<String, ()>
 {
-	if is_std_path(nav)
+	if is_std_path(relative)
 	{
-		return Ok(nav.to_string());
+		return Ok(relative.to_string());
 	}
 
 	let current = current.replace("\\", "/");
-	let nav = nav.replace("\\", "/");
+	let nav = relative.replace("\\", "/");
 
-	filename_validate(
+	filename_validate_relative(
 		report,
 		span,
 		&nav)?;
@@ -79,15 +79,26 @@ pub fn filename_navigate(
 		path_components.clear();
 	}
 
-	// Add the new path components
-	for split in nav.split("/")
+	// Add the new path components, collapsing `.` and empty components
+	let relative_components: Vec<&str> = nav
+		.split("/")
+		.filter(|s| s.len() > 0 && s != &".")
+		.collect();
+
+	if relative_components.len() == 0
+	{
+		report.error_span(
+			"invalid filename",
+			span);
+		
+		return Err(());
+	}
+		
+	for split in relative_components
 	{
 		path_components.push(split);
 	}
 
-	// Collapse `.` and empty components
-	path_components.retain(|s| s.len() > 0 && s != &".");
-
 	// Collapse `..` components
 	let mut new_path_components = Vec::new();
 	for i in 0..path_components.len()
@@ -119,5 +130,17 @@ pub fn filename_navigate(
 		}
 	}
 
+	if new_path_components.len() == 0 ||
+		new_filename == "" ||
+		new_filename == "." ||
+		new_filename == "/"
+	{
+		report.error_span(
+			"invalid filename",
+			span);
+		
+		return Err(());
+	}
+
 	Ok(new_filename)
 }
\ No newline at end of file
diff --git a/src/util/mod.rs b/src/util/mod.rs
index f15cc26d..63fb589d 100644
--- a/src/util/mod.rs
+++ b/src/util/mod.rs
@@ -24,11 +24,11 @@ pub use self::fileserver::{
     FILESERVER_MOCK_WRITE_FILENAME_SUFFIX,
 };
 
-mod filename;
-pub use self::filename::{
+mod file_navigation;
+pub use self::file_navigation::{
     STD_PATH_PREFIX,
     is_std_path,
-    filename_validate,
+    filename_validate_relative,
     filename_navigate,
 };