diff --git a/tests/check_assets.sh b/tests/check_assets.sh
old mode 100644
new mode 100755
index e19ede6..781d019
--- a/tests/check_assets.sh
+++ b/tests/check_assets.sh
@@ -1,7 +1,9 @@
 #!/bin/bash
 
-if [ -f config.sh ]; then
-    . config.sh
+BASEDIR=`dirname $0`
+
+if [ -f $BASEDIR/config.sh ]; then
+    . $BASEDIR/config.sh
 fi
 
 if [ -z "$POSTS_DIR" ]
@@ -16,14 +18,33 @@ then
     exit 2
 fi
 
-rc=0
-sed -rn 's|^.*\!\[.*\]\(%assets_url%/(.*)\)$|\1|p' $POSTS_DIR/* | while read line
-do
-    if [ ! -f "$ASSETS_DIR/$line" ]
-    then
-        echo "$line not found"
-        rc=1
-    fi
-done
+function check(){
+    local rc=0
+    sed -rn 's|^.*\!\[.*\]\(%assets_url%/(.*)\)$|\1|p' $1 | while read line
+    do
+        if [ ! -f "$BASEDIR/$ASSETS_DIR/$line" ]
+        then
+            echo "`basename $1`: $line not found" >&2
+            rc=1
+        fi
+    done
+    return $rc
+}
+
+if [ -z "$1" ]
+then
+    rc=0
+    for file in $BASEDIR/$POSTS_DIR/*
+    do
+        check $file
+        if [ $? -ne 0 ]
+        then
+            rc=1
+        fi
+    done
+else
+    check $BASEDIR/$POSTS_DIR/$1
+    rc=$?
+fi
 
 exit $rc