diff --git a/dune/fufem/formatstring.hh b/dune/fufem/formatstring.hh
index 5d9e773523d2df3ba0f1800b6d802fcaf80eb426..30a3002ab42498e703984748756bfc6cad84f2e0 100644
--- a/dune/fufem/formatstring.hh
+++ b/dune/fufem/formatstring.hh
@@ -21,7 +21,7 @@ std::string formatString(const std::string& s, const T&... args)
     static const int bufferSize=1000;
     char buffer[bufferSize];
 
-    r = std::snprintf(buffer, s.c_str(), bufferSize, args...);
+    int r = std::snprintf(buffer, bufferSize, s.c_str(), args...);
 
     // negative return values correspond to errors
     if (r<0)
@@ -37,7 +37,7 @@ std::string formatString(const std::string& s, const T&... args)
     char* dynamicBuffer = new char[dynamicBufferSize];
 
     // convert and check for errors again
-    r = std::snprintf(dynamicBuffer, s.c_str(), dynamicBufferSize, args...);
+    r = std::snprintf(dynamicBuffer, dynamicBufferSize, s.c_str(), args...);
     if (r<0)
         DUNE_THROW(Dune::Exception,"Could not convert format string using given arguments.");