diff --git a/MathLib/LinAlg/PETSc/PETScMatrix.cpp b/MathLib/LinAlg/PETSc/PETScMatrix.cpp
index aa82da6c159e0a94f320b21d772eb8d5fcd2e0b2..5c504d2488bae67cd922dac25670d56cd6a0f5a9 100644
--- a/MathLib/LinAlg/PETSc/PETScMatrix.cpp
+++ b/MathLib/LinAlg/PETSc/PETScMatrix.cpp
@@ -75,7 +75,7 @@ void PETScMatrix::viewer(const std::string &file_name, const PetscViewerFormat v
     MatView(_A,viewer);
 
 // This preprocessor is only for debugging, e.g. dump the matrix and exit the program.
-// To activate, remove 'non' in ths following line.  
+// To activate, remove 'non' in the following line.  
 #define nonEXIT_TEST  
 #ifdef EXIT_TEST
     MatDestroy(&_A);