diff --git a/src/main/kotlin/net/shadowfacts/asmr/program/ExecutableBlock.kt b/src/main/kotlin/net/shadowfacts/asmr/program/ExecutableBlock.kt
index 10bb8d4..c6e7df9 100644
--- a/src/main/kotlin/net/shadowfacts/asmr/program/ExecutableBlock.kt
+++ b/src/main/kotlin/net/shadowfacts/asmr/program/ExecutableBlock.kt
@@ -7,7 +7,7 @@ import net.minecraft.util.Identifier
  */
 abstract class ExecutableBlock(identifier: Identifier): ProgramBlock(identifier) {
 
-	open val executionFlow = ExecutionFlow(this)
+	abstract val executionFlow: ExecutionFlow
 
 	abstract fun execute()
 
diff --git a/src/main/kotlin/net/shadowfacts/asmr/program/ExecutionFlow.kt b/src/main/kotlin/net/shadowfacts/asmr/program/ExecutionFlow.kt
index 7ddf41e..f8aaee4 100644
--- a/src/main/kotlin/net/shadowfacts/asmr/program/ExecutionFlow.kt
+++ b/src/main/kotlin/net/shadowfacts/asmr/program/ExecutionFlow.kt
@@ -3,14 +3,20 @@ package net.shadowfacts.asmr.program
 /**
  * @author shadowfacts
  */
-open class ExecutionFlow(val block: ExecutableBlock) {
+interface ExecutionFlow {
+	val block: ExecutableBlock
 
-	open var next: ExecutableBlock? = null
-	open var prev: ExecutableBlock? = null
+	val next: ExecutableBlock?
+	val prev: ExecutableBlock?
+}
+class DirectExecutionFlow(override val block: ExecutableBlock): ExecutionFlow {
+	override var next: ExecutableBlock? = null
+	override var prev: ExecutableBlock? = null
 
 	fun link(next: ExecutableBlock) {
 		this.next = next
-		next.executionFlow.prev = block
+		(next.executionFlow as? DirectExecutionFlow)?.let {
+			it.prev = block
+		}
 	}
-
-}
\ No newline at end of file
+}
diff --git a/src/main/kotlin/net/shadowfacts/asmr/program/blocks/PrintBlock.kt b/src/main/kotlin/net/shadowfacts/asmr/program/blocks/PrintBlock.kt
index 4aeceed..a00cf3a 100644
--- a/src/main/kotlin/net/shadowfacts/asmr/program/blocks/PrintBlock.kt
+++ b/src/main/kotlin/net/shadowfacts/asmr/program/blocks/PrintBlock.kt
@@ -19,6 +19,8 @@ class PrintBlock<Type: Any>(
 	override val inputs: Array<ProgramBlockInput<*>> = arrayOf(input)
 	override val outputs: Array<ProgramBlockOutput<*>> = arrayOf()
 
+	override val executionFlow = DirectExecutionFlow(this)
+
 	override fun execute() {
 		println(input.value)
 	}
diff --git a/src/main/kotlin/net/shadowfacts/asmr/program/blocks/StartBlock.kt b/src/main/kotlin/net/shadowfacts/asmr/program/blocks/StartBlock.kt
index 33fdac3..daecfe0 100644
--- a/src/main/kotlin/net/shadowfacts/asmr/program/blocks/StartBlock.kt
+++ b/src/main/kotlin/net/shadowfacts/asmr/program/blocks/StartBlock.kt
@@ -2,9 +2,7 @@ package net.shadowfacts.asmr.program.blocks
 
 import net.minecraft.util.Identifier
 import net.shadowfacts.asmr.ASMR
-import net.shadowfacts.asmr.program.ExecutableBlock
-import net.shadowfacts.asmr.program.ProgramBlockInput
-import net.shadowfacts.asmr.program.ProgramBlockOutput
+import net.shadowfacts.asmr.program.*
 
 /**
  * @author shadowfacts
@@ -16,6 +14,8 @@ class StartBlock: ExecutableBlock(
 	override val inputs: Array<ProgramBlockInput<*>> = arrayOf()
 	override val outputs: Array<ProgramBlockOutput<*>> = arrayOf()
 
+	override val executionFlow = DirectExecutionFlow(this)
+
 	override fun execute() {
 	}
 
diff --git a/src/main/kotlin/net/shadowfacts/asmr/program/blocks/math/BinaryOperatorBlock.kt b/src/main/kotlin/net/shadowfacts/asmr/program/blocks/math/BinaryOperatorBlock.kt
index 3e7a487..42e75c6 100644
--- a/src/main/kotlin/net/shadowfacts/asmr/program/blocks/math/BinaryOperatorBlock.kt
+++ b/src/main/kotlin/net/shadowfacts/asmr/program/blocks/math/BinaryOperatorBlock.kt
@@ -2,10 +2,7 @@ package net.shadowfacts.asmr.program.blocks.math
 
 import net.minecraft.util.Identifier
 import net.shadowfacts.asmr.ASMR
-import net.shadowfacts.asmr.program.ExecutableBlock
-import net.shadowfacts.asmr.program.ProgramBlockInput
-import net.shadowfacts.asmr.program.ProgramBlockOutput
-import net.shadowfacts.asmr.program.ProgramType
+import net.shadowfacts.asmr.program.*
 import java.lang.RuntimeException
 
 /**
@@ -32,6 +29,8 @@ class BinaryOperatorBlock<Type: Any>(
 	override val inputs: Array<ProgramBlockInput<*>> = arrayOf(left, right)
 	override val outputs: Array<ProgramBlockOutput<*>> = arrayOf(output)
 
+	override val executionFlow = DirectExecutionFlow(this)
+
 	override fun execute() {
 		if (type == ProgramType.INT) {
 			val left = left.value as Int