diff --git a/code/BaseImporter.cpp b/code/BaseImporter.cpp
index 6fdb3b3b5..a3ed91acb 100644
--- a/code/BaseImporter.cpp
+++ b/code/BaseImporter.cpp
@@ -118,7 +118,11 @@ void BaseImporter::GetExtensionList(std::set<std::string>& extensions)
 	do {
 		if (!*ext || *ext == ' ') {
 			extensions.insert(std::string(last,ext-last));
-			last = ext+1;
+			ai_assert(ext-last > 0);
+			last = ext;
+			while(*last == ' ') {
+				++last;
+			}
 		}
 	}
 	while(*ext++);