diff --git a/Changelog.md b/Changelog.md
index a24ac211c..8fa54c818 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -3,6 +3,7 @@
 Features:
 
 Bugfixes:
+ * Type checker: forbid signed exponential that led to an incorrect use of EXP opcode.
 
 ### 0.4.3 (2016-10-25)
 
diff --git a/libsolidity/ast/Types.cpp b/libsolidity/ast/Types.cpp
index 7cfed3c88..7fe97fa76 100644
--- a/libsolidity/ast/Types.cpp
+++ b/libsolidity/ast/Types.cpp
@@ -349,11 +349,14 @@ TypePointer IntegerType::binaryOperatorResult(Token::Value _operator, TypePointe
 		return commonType;
 	if (Token::isBooleanOp(_operator))
 		return TypePointer();
-	// Nothing else can be done with addresses
 	if (auto intType = dynamic_pointer_cast<IntegerType const>(commonType))
 	{
+		// Nothing else can be done with addresses
 		if (intType->isAddress())
 			return TypePointer();
+		// Signed EXP is not allowed
+		if (Token::Exp == _operator && intType->isSigned())
+			return TypePointer();
 	}
 	else if (auto fixType = dynamic_pointer_cast<FixedPointType const>(commonType))
 		if (Token::Exp == _operator)