diff --git a/pkg/compiler/codegen.go b/pkg/compiler/codegen.go
index 212919adf..25aa5cb31 100644
--- a/pkg/compiler/codegen.go
+++ b/pkg/compiler/codegen.go
@@ -1173,7 +1173,13 @@ func (c *codegen) convertBuiltin(expr *ast.CallExpr) {
 
 	switch name {
 	case "len":
+		emit.Opcode(c.prog.BinWriter, opcode.DUP)
+		emit.Opcode(c.prog.BinWriter, opcode.ISNULL)
+		emit.Instruction(c.prog.BinWriter, opcode.JMPIF, []byte{2 + 1 + 2})
 		emit.Opcode(c.prog.BinWriter, opcode.SIZE)
+		emit.Instruction(c.prog.BinWriter, opcode.JMP, []byte{2 + 1 + 1})
+		emit.Opcode(c.prog.BinWriter, opcode.DROP)
+		emit.Opcode(c.prog.BinWriter, opcode.PUSH0)
 	case "append":
 		arg := expr.Args[0]
 		typ := c.typeInfo.Types[arg].Type
@@ -1515,7 +1521,8 @@ func (c *codegen) writeJumps(b []byte) error {
 		case opcode.JMP, opcode.JMPIFNOT, opcode.JMPIF, opcode.CALL,
 			opcode.JMPEQ, opcode.JMPNE,
 			opcode.JMPGT, opcode.JMPGE, opcode.JMPLE, opcode.JMPLT:
-			panic("short jumps are not yet supported")
+			// Noop, assumed to be correct already. If you're fixing #905,
+			// make sure not to break "len" handling above.
 		case opcode.JMPL, opcode.JMPIFL, opcode.JMPIFNOTL,
 			opcode.JMPEQL, opcode.JMPNEL,
 			opcode.JMPGTL, opcode.JMPGEL, opcode.JMPLEL, opcode.JMPLTL,
diff --git a/pkg/compiler/interop_test.go b/pkg/compiler/interop_test.go
index 646670244..7180b85bd 100644
--- a/pkg/compiler/interop_test.go
+++ b/pkg/compiler/interop_test.go
@@ -187,3 +187,14 @@ func TestBuiltinPackage(t *testing.T) {
 	}`
 	eval(t, src, big.NewInt(1))
 }
+
+func TestLenForNil(t *testing.T) {
+	src := `
+	package foo
+	func Main() bool {
+		var a []int = nil
+		return len(a) == 0
+	}`
+
+	eval(t, src, true)
+}
diff --git a/pkg/compiler/syscall.go b/pkg/compiler/syscall.go
index be1b8a9c9..9b725a1c4 100644
--- a/pkg/compiler/syscall.go
+++ b/pkg/compiler/syscall.go
@@ -1,6 +1,10 @@
 package compiler
 
 var syscalls = map[string]map[string]string{
+	"binary": {
+		"Serialize":   "System.Binary.Serialize",
+		"Deserialize": "System.Binary.Deserialize",
+	},
 	"crypto": {
 		"ECDsaVerify": "Neo.Crypto.ECDsaVerify",
 	},
@@ -37,8 +41,6 @@ var syscalls = map[string]map[string]string{
 		"Notify":       "System.Runtime.Notify",
 		"Log":          "System.Runtime.Log",
 		"GetTime":      "System.Runtime.GetTime",
-		"Serialize":    "System.Binary.Serialize",
-		"Deserialize":  "System.Binary.Deserialize",
 	},
 	"blockchain": {
 		"GetBlock":                "System.Blockchain.GetBlock",
diff --git a/pkg/interop/runtime/runtime.go b/pkg/interop/runtime/runtime.go
index 5695fa780..558362c65 100644
--- a/pkg/interop/runtime/runtime.go
+++ b/pkg/interop/runtime/runtime.go
@@ -43,16 +43,22 @@ func GetTrigger() byte {
 	return 0x00
 }
 
+// System returns the System trigger type value to compare with
+// GetTrigger return value.
+func System() byte {
+	return 0x01
+}
+
 // Application returns the Application trigger type value to compare with
 // GetTrigger return value.
 func Application() byte {
-	return 0x10
+	return 0x40
 }
 
 // Verification returns the Verification trigger type value to compare with
 // GetTrigger return value.
 func Verification() byte {
-	return 0x00
+	return 0x20
 }
 
 // GasLeft returns the amount of gas available for the current execution.