diff --git a/libethereum/Instruction.cpp b/libethereum/Instruction.cpp
index 58e5d045a..130793f93 100644
--- a/libethereum/Instruction.cpp
+++ b/libethereum/Instruction.cpp
@@ -761,7 +761,7 @@ static int compileLispFragment(char const*& d, char const* e, bool _quiet, bytes
 					vector<unsigned> locs;
 					map<string, unsigned> vars;
 					if (compileLispFragment(d, e, _quiet, codes, locs, _vars) == -1)
-						break;
+						return false;
 					unsigned codeLoc = o_code.size() + 5 + 1;
 					o_locs.push_back(o_code.size());
 					pushLocation(o_code, codeLoc + codes.size());
@@ -769,13 +769,28 @@ static int compileLispFragment(char const*& d, char const* e, bool _quiet, bytes
 					for (auto b: codes)
 						o_code.push_back(b);
 
+					bytes ncode[1];
+					vector<unsigned> nlocs[1];
+					if (compileLispFragment(d, e, _quiet, ncode[0], nlocs[0], _vars) != 1)
+						return false;
+
 					pushLiteral(o_code, codes.size());
+					o_code.push_back((byte)Instruction::DUP);
+					int o = compileLispFragment(d, e, _quiet, o_code, o_locs, _vars);
+					if (o == 1)
+					{
+						o_code.push_back((byte)Instruction::LT);
+						o_code.push_back((byte)Instruction::NOT);
+						o_code.push_back((byte)Instruction::MUL);
+						o_code.push_back((byte)Instruction::DUP);
+					}
+					else if (o != -1)
+						return false;
+
 					o_locs.push_back(o_code.size());
 					pushLocation(o_code, codeLoc);
-					if (compileLispFragment(d, e, _quiet, o_code, o_locs, _vars) != 1)
-						break;
+					appendCode(o_code, o_locs, ncode[0], nlocs[0]);
 					o_code.push_back((byte)Instruction::CODECOPY);
-					pushLiteral(o_code, codes.size());
 					outs = 1;
 				}
 				else if (t == "&&")