diff --git a/bin/test.sh b/bin/test.sh
index 1b8254771f14a9ad4b570c171df3f3b4a73a5e23..4192edf44b67e3543adec4bf0cf413d13a0d02fe 100755
--- a/bin/test.sh
+++ b/bin/test.sh
@@ -31,7 +31,7 @@ SAVE=
 
 DUNE_OPT=
 DUNE_LOG=./.test-errors.log
-CACHEDIR=./.wp-cache
+CACHEDIR=$(pwd -P)/.wp-cache
 FRAMAC_WP_CACHE_GIT=git@git.frama-c.com:frama-c/wp-cache.git
 
 # --------------------------------------------------------------------------
@@ -73,7 +73,7 @@ function Usage
     echo ""
     echo "  FRAMAC_WP_QUALIF"
     echo "  FRAMAC_WP_CACHEDIR"
-    echo "    Location of wp-cache ($FRAMAC_WP_CACHEDIR)"
+    echo "    Absolute path to wp-cache directory ($FRAMAC_WP_CACHEDIR)"
     if [ ! -d $FRAMAC_WP_CACHEDIR ]; then
         echo "    About to clone from $FRAMAC_WP_CACHE_GIT"
     fi
@@ -142,6 +142,11 @@ function SetEnv
     [ ! -f "$FRAMAC_WP_CACHEDIR" ] || [ -d "$FRAMAC_WP_CACHEDIR" ] \
         || Error "$FRAMAC_WP_CACHEDIR is not a directory"
 
+    case "$FRAMAC_WP_CACHEDIR" in
+        /*);;
+        *) Error "Requires an absolute path to $FRAMAC_WP_CACHEDIR";;
+    esac
+
 }
 
 function CloneCache
diff --git a/share/Makefile.testing b/share/Makefile.testing
index e7fae696d932676377473f5b3efdd4f2933dc7fa..9aa2d68a31b8c53db89745c1ea887b50b59d9f17 100644
--- a/share/Makefile.testing
+++ b/share/Makefile.testing
@@ -47,6 +47,11 @@ else
 FRAMAC_WP_CACHEDIR?=
 endif
 
+ifeq ($(PTEST_USE_WP_CACHE),yes)
+# we need these variable to be present in the shell environment of the commands
+export FRAMAC_WP_CACHEDIR FRAMAC_WP_CACHE
+endif
+
 ############
 # Default values necessary for make -f <this-makefile>
 
diff --git a/src/plugins/wp/tests/README.md b/src/plugins/wp/tests/README.md
index 3d90fddfa98c31cc044c5f1bbcd7e4df7775e89a..f1d1bc29cf9349d365c4b13aaddce54f531d584d 100644
--- a/src/plugins/wp/tests/README.md
+++ b/src/plugins/wp/tests/README.md
@@ -48,6 +48,8 @@ The `./bin/test.sh` uses, in order of proprity:
 - `FRAMAC_WP_CACHEDIR` environement variable,
 - local `./.wp-cache` directory.
 
+Of course, these environment variables must be set to an absolute path to prevent from different execution locations of Frama-C.
+
 It is _not_ recommended to use the `FRAMAC_WP_CACHEDIR` variable in your default
 shell setup, unless is it a temporary directory (eg. `/tmp/wp-sandbox`) since
 _every_ run of `frama-c -wp` might then use it by default. Be carefull if you do so.