diff --git a/src/vm.ts b/src/vm.ts
index 197b6ab..1620571 100644
--- a/src/vm.ts
+++ b/src/vm.ts
@@ -430,6 +430,9 @@ export class VM {
         if (fn.variadic) fixedParamCount--
         if (fn.named) fixedParamCount--
 
+        // Track which positional args have been consumed
+        let positionalArgIndex = 0
+
         // Bind fixed parameters using priority: named arg > positional arg > default > null
         for (let i = 0; i < fixedParamCount; i++) {
           const paramName = fn.params[i]!
@@ -438,8 +441,9 @@ export class VM {
           if (namedArgs.has(paramName)) {
             this.scope.set(paramName, namedArgs.get(paramName)!)
             namedArgs.delete(paramName) // Remove from named args so it won't go to named
-          } else if (positionalArgs[i] !== undefined) {
-            this.scope.set(paramName, positionalArgs[i]!)
+          } else if (positionalArgIndex < positionalArgs.length) {
+            this.scope.set(paramName, positionalArgs[positionalArgIndex]!)
+            positionalArgIndex++
           } else if (fn.defaults[paramName] !== undefined) {
             const defaultIdx = fn.defaults[paramName]!
             const defaultValue = this.constants[defaultIdx]!
@@ -454,7 +458,7 @@ export class VM {
         // Handle variadic parameter (collect remaining positional args)
         if (fn.variadic) {
           const variadicParamName = fn.params[fn.params.length - (fn.named ? 2 : 1)]!
-          const remainingArgs = positionalArgs.slice(fixedParamCount)
+          const remainingArgs = positionalArgs.slice(positionalArgIndex)
           this.scope.set(variadicParamName, { type: 'array', value: remainingArgs })
         }
 
@@ -509,6 +513,9 @@ export class VM {
         if (tailFn.variadic) tailFixedParamCount--
         if (tailFn.named) tailFixedParamCount--
 
+        // Track which positional args have been consumed
+        let tailPositionalArgIndex = 0
+
         // Bind fixed parameters
         for (let i = 0; i < tailFixedParamCount; i++) {
           const paramName = tailFn.params[i]!
@@ -516,8 +523,9 @@ export class VM {
           if (tailNamedArgs.has(paramName)) {
             this.scope.set(paramName, tailNamedArgs.get(paramName)!)
             tailNamedArgs.delete(paramName)
-          } else if (tailPositionalArgs[i] !== undefined) {
-            this.scope.set(paramName, tailPositionalArgs[i]!)
+          } else if (tailPositionalArgIndex < tailPositionalArgs.length) {
+            this.scope.set(paramName, tailPositionalArgs[tailPositionalArgIndex]!)
+            tailPositionalArgIndex++
           } else if (tailFn.defaults[paramName] !== undefined) {
             const defaultIdx = tailFn.defaults[paramName]!
             const defaultValue = this.constants[defaultIdx]!
@@ -532,7 +540,7 @@ export class VM {
         // Handle variadic parameter
         if (tailFn.variadic) {
           const variadicParamName = tailFn.params[tailFn.params.length - (tailFn.named ? 2 : 1)]!
-          const remainingArgs = tailPositionalArgs.slice(tailFixedParamCount)
+          const remainingArgs = tailPositionalArgs.slice(tailPositionalArgIndex)
           this.scope.set(variadicParamName, { type: 'array', value: remainingArgs })
         }