diff --git a/tests/lbpm_morphopen_pp.cpp b/tests/lbpm_morphopen_pp.cpp
index 0f3cd4cb..b8f1ff4e 100644
--- a/tests/lbpm_morphopen_pp.cpp
+++ b/tests/lbpm_morphopen_pp.cpp
@@ -397,7 +397,7 @@ int main(int argc, char **argv)
 		}
 
 		sprintf(LocalRankFilename,"ID.%05i",rank);
-		FILE *ID = fopen(LocalRankFilename,"wb");
+		ID = fopen(LocalRankFilename,"wb");
 		fwrite(id,1,N,ID);
 		fclose(ID);
 	}