diff --git a/src/gvcore/imageloader.cpp b/src/gvcore/imageloader.cpp
index 406a378..17aedf2 100644
--- a/src/gvcore/imageloader.cpp
+++ b/src/gvcore/imageloader.cpp
@@ -444,7 +444,12 @@ static TQString mimeTypeFromFormat(const char* format) {
 	TQStringList formats = KImageIO::types(KImageIO::Reading);
 	TQStringList mimeTypes = KImageIO::mimeTypes(KImageIO::Reading);
 	int pos = formats.findIndex(TQString::fromAscii(format));
-	Q_ASSERT(pos != -1);
+	if(pos < 0) {
+		// TQImageIO::imageFormat() nay return some different types than listed by
+		// TQImage::inputFormats(), e.g. "PPMRAW". Also TDE might simly be ignorant
+		// abous some types known to TQt.
+		return TQString::null;
+	}
 	return mimeTypes[pos];
 }
 
@@ -463,13 +468,18 @@ void ImageLoader::slotDataReceived(TDEIO::Job* job, const TQByteArray& chunk) {
 		const char* format = TQImageIO::imageFormat(&buffer);
 		if (format) {
 			// This is a raster image, get the mime type now
-			d->mURLKind = MimeTypeUtils::KIND_RASTER_IMAGE;
 			d->mMimeType = mimeTypeFromFormat(format);
+			if(d->mMimeType.isNull()) { // fall back to TDE's autoguess of mime by content
+				KMimeType::Ptr ptr = KMimeType::findByContent(d->mRawData);
+				d->mMimeType = ptr->name();
+			}
+			d->mURLKind = MimeTypeUtils::KIND_RASTER_IMAGE;
 		} else {
 			KMimeType::Ptr ptr = KMimeType::findByContent(d->mRawData);
 			d->mMimeType = ptr->name();
 			d->mURLKind = MimeTypeUtils::mimeTypeKind(d->mMimeType);
 		}
+
 		if (d->mURLKind!=MimeTypeUtils::KIND_RASTER_IMAGE) {
 			Q_ASSERT(!d->mDecoderTimer.isActive());
 			job->kill(true /* quietly */);