diff --git a/scripts/check-non-ascii-characters.sh b/scripts/check-non-ascii-characters.sh
index d4778a9256dc6642f189568dbf453d827436e234..9fadd43a931af4030c10af5eb3cb131ee16f766b 100755
--- a/scripts/check-non-ascii-characters.sh
+++ b/scripts/check-non-ascii-characters.sh
@@ -20,9 +20,12 @@ fi
 echo "Upstream name is :" $UPSTREAM
 
 BASE_COMMIT=$UPSTREAM/master
-CHANGED_FILES=$(git diff --name-only $BASE_COMMIT)
+# check only source code files
+CHANGED_FILES=$(git diff --name-only $BASE_COMMIT | grep -E '.*\.(h|hpp|c|C|cpp|cxx|tpl)$' | grep -viE '.*LinkDef.h$')
+
 for file in $CHANGED_FILES; do
-  result=$(file $file | grep UTF-8)
+  # find all source code files which are non ASCII ones
+  result=$(file $file | grep -v ASCII)
   if [[ "$result" != "" ]]; then
     echo " "
     echo "File $file contains non ASCII characters"