diff --git a/Foundation/include/Poco/NumericString.h b/Foundation/include/Poco/NumericString.h
index 8dc18abdb..4bb7dca35 100644
--- a/Foundation/include/Poco/NumericString.h
+++ b/Foundation/include/Poco/NumericString.h
@@ -110,6 +110,8 @@ bool strToInt(const char* pStr, I& result, short base, char thSep = ',')
 	char sign = 1;
 	if ((base == 10) && (*pStr == '-'))
 	{
+		// Unsigned types can't be negative so abort parsing
+		if (std::numeric_limits<I>::min() >= 0) return false;
 		sign = -1;
 		++pStr;
 	}
diff --git a/Foundation/testsuite/src/NumberParserTest.cpp b/Foundation/testsuite/src/NumberParserTest.cpp
index 967236263..7ee05e693 100644
--- a/Foundation/testsuite/src/NumberParserTest.cpp
+++ b/Foundation/testsuite/src/NumberParserTest.cpp
@@ -272,6 +272,12 @@ void NumberParserTest::testParseError()
 		failmsg("must throw SyntaxException");
 	} catch (SyntaxException&) { }
 
+	try
+	{
+		NumberParser::parseUnsigned("-123");
+		failmsg("must throw SyntaxException");
+	} catch (SyntaxException&) { }
+
 	try
 	{
 		NumberParser::parseHex("z23");