diff --git a/tests/lbpm_morphopen_pp.cpp b/tests/lbpm_morphopen_pp.cpp
index b8f1ff4e..13df38fd 100644
--- a/tests/lbpm_morphopen_pp.cpp
+++ b/tests/lbpm_morphopen_pp.cpp
@@ -106,6 +106,7 @@ int main(int argc, char **argv)
 		char *id;
 		id = new char [N];
 
+		nx+=2; ny+=2; nz+=2;
 		DoubleArray SignDist(nx,ny,nz);
 		// Read the signed distance from file
 		sprintf(LocalRankFilename,"SignDist.%05i",rank);