diff --git a/internal/compiler/compiler.go b/internal/compiler/compiler.go
index 22e0c83..77ef6c4 100644
--- a/internal/compiler/compiler.go
+++ b/internal/compiler/compiler.go
@@ -34,8 +34,28 @@ func (c *Compiler) Registry() *CommandRegistry {
 // Compile processes preprocessed lines and generates assembly output
 func (c *Compiler) Compile(lines []preproc.Line) ([]string, error) {
 	var codeOutput []string
+	var lastKind = preproc.Source
 
 	for _, line := range lines {
+		// Detect kind transitions and emit markers
+		if line.Kind != lastKind {
+			// Close previous block
+			if lastKind == preproc.Assembler {
+				codeOutput = append(codeOutput, "; ENDASM")
+			} else if lastKind == preproc.Script {
+				codeOutput = append(codeOutput, "; ENDSCRIPT")
+			}
+
+			// Open new block
+			if line.Kind == preproc.Assembler {
+				codeOutput = append(codeOutput, "; ASM")
+			} else if line.Kind == preproc.Script {
+				codeOutput = append(codeOutput, "; SCRIPT")
+			}
+
+			lastKind = line.Kind
+		}
+
 		// Skip non-source lines (assembler and script handled differently)
 		if line.Kind != preproc.Source {
 			if line.Kind == preproc.Assembler {
@@ -88,6 +108,15 @@ func (c *Compiler) Compile(lines []preproc.Line) ([]string, error) {
 		codeOutput = append(codeOutput, asmLines...)
 	}
 
+	// Close any open block
+	if lastKind == preproc.Assembler {
+		//codeOutput = append(codeOutput, "; ENDASM")
+		return nil, fmt.Errorf("Unclosed ASM block.")
+	} else if lastKind == preproc.Script {
+		//codeOutput = append(codeOutput, "; ENDSCRIPT")
+		return nil, fmt.Errorf("Unclosed SCRIPT block.")
+	}
+
 	// Assemble final output with headers and footers
 	return c.assembleOutput(codeOutput), nil
 }