diff --git a/src/material_header.F90 b/src/material_header.F90
index dc1ae4a35a..be126aa8b3 100644
--- a/src/material_header.F90
+++ b/src/material_header.F90
@@ -3,7 +3,7 @@ module material_header
   implicit none
 
 !===============================================================================
-! MATERIAL describes a material by its constituent isotopes
+! MATERIAL describes a material by its constituent nuclides
 !===============================================================================
 
   type Material
diff --git a/src/source_header.F90 b/src/source_header.F90
index 76e7ac2ada..fce47ab1d3 100644
--- a/src/source_header.F90
+++ b/src/source_header.F90
@@ -8,7 +8,7 @@ module source_header
 !===============================================================================
 
   type ExtSource
-     integer :: type_space              ! spacial distributione, e.g. 'box' or 'point'
+     integer :: type_space              ! spacial distribution, e.g. 'box' or 'point'
      integer :: type_angle              ! angle distribution, e.g. 'isotropic'
      integer :: type_energy             ! energy distribution, e.g. 'Watt'
      real(8), allocatable :: params_space(:) ! parameters for spatial distribution