diff --git a/pyext/Makefile.am b/pyext/Makefile.am
index 83d10bd..84fa8f9 100755
--- a/pyext/Makefile.am
+++ b/pyext/Makefile.am
@@ -69,7 +69,7 @@ all-local: build
 
 # Build the gammalib extension module
 build: $(BUILT_SOURCES)
-	$(PYTHON) setup.py build_ext
+	@PYTHON_BUILD_PREFIX@ $(PYTHON) setup.py build_ext
 
 # If 'make check' is invoked we build the extension modules inplace, so that
 # putting the 'pyext' directory in the PYTHONPATH allows importing the gammalib
@@ -77,7 +77,7 @@ build: $(BUILT_SOURCES)
 # linking with libgamma, which will allow a successful 'make check' on systems
 # (such as Mac OS X) that have fixed shared library paths.
 check-local:
-	$(PYTHON) setup.py build_ext --inplace
+	@PYTHON_BUILD_PREFIX@ $(PYTHON) setup.py build_ext --inplace
 
 # Install the gammalib extension module
 install-exec-local: