diff --git a/test/Makefile.am b/test/Makefile.am
index 5c42dd4..9478ac9 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -36,7 +36,7 @@ endif
 # Optional python bindings
 if WITH_PYTHON
   TEST_PYTHON_SCRIPT = test_python.py
-  TEST_PYTHON_ENV    = PYTHONPATH=$(top_builddir)/pyext$(TEST_MWL)$(TEST_CTA)$(TEST_LAT):$(PYTHONPATH)
+  TEST_PYTHON_ENV    = PYTHONPATH=$(top_builddir)/pyext:$(top_builddir)/pyext/build/gammalib$(TEST_MWL)$(TEST_CTA)$(TEST_LAT):$(PYTHONPATH)
 endif
 
 # Darwin support