diff --git a/engines/parallaction/iff.cpp b/engines/parallaction/iff.cpp
index c48b12f888d..8f8ba0a838d 100644
--- a/engines/parallaction/iff.cpp
+++ b/engines/parallaction/iff.cpp
@@ -39,6 +39,22 @@ void IFFParser::setInputStream(Common::SeekableReadStream *stream) {
 	_stream = stream;
 	_startOffset = 0;
 	_endOffset = _stream->size();
+
+	_formType = 0;
+	_formSize = (uint32)-1;
+
+	if (_stream->size() < 12) {
+		// this file is too small to be a valid IFF container
+		return;
+	}
+
+	if (_stream->readUint32BE() != ID_FORM) {
+		// no FORM header was found
+		return;
+	}
+
+	_formSize = _stream->readUint32BE();
+	_formType = _stream->readUint32BE();
 }
 
 void IFFParser::destroy() {
@@ -46,18 +62,12 @@ void IFFParser::destroy() {
 	_startOffset = _endOffset = 0;
 }
 
-uint32 IFFParser::getFORMBlockSize() {
-	uint32 oldOffset = _stream->pos();
+uint32 IFFParser::getFORMSize() const {
+	return _formSize;
+}
 
-	uint32 data = _stream->readUint32BE();
-
-	if (data != ID_FORM) {
-		_stream->seek(oldOffset);
-		return (uint32)-1;
-	}
-
-	data = _stream->readUint32BE();
-	return data;
+Common::IFF_ID IFFParser::getFORMType() const {
+	return _formType;
 }
 
 uint32 IFFParser::moveToIFFBlock(Common::IFF_ID chunkName) {
@@ -117,6 +127,10 @@ ILBMDecoder::ILBMDecoder(Common::SeekableReadStream *in, bool disposeStream) : _
 	assert(in);
 	_parser.setInputStream(in);
 
+	if (_parser.getFORMType() != ID_ILBM) {
+		return;
+	}
+
 	_hasHeader = _parser.loadIFFBlock(ID_BMHD, &_header, sizeof(_header));
 	if (!_hasHeader) {
 		return;
diff --git a/engines/parallaction/iff.h b/engines/parallaction/iff.h
index 6edd28a17f1..43f78bf001c 100644
--- a/engines/parallaction/iff.h
+++ b/engines/parallaction/iff.h
@@ -46,7 +46,9 @@ public:
 
 	operator bool() const { return (_startOffset != _endOffset) && _stream; }
 
-	uint32 getFORMBlockSize();
+	uint32 getFORMSize() const;
+	Common::IFF_ID getFORMType() const;
+
 	uint32 getIFFBlockSize(Common::IFF_ID chunk);
 	bool loadIFFBlock(Common::IFF_ID chunk, void *loadTo, uint32 ptrSize);
 	Common::SeekableReadStream *getIFFBlockStream(Common::IFF_ID chunkName);
@@ -57,6 +59,9 @@ private:
 	Common::SeekableReadStream *_stream;
 	uint32 _startOffset;
 	uint32 _endOffset;
+
+	uint32 _formSize;
+	Common::IFF_ID _formType;
 };