diff --git a/setup.py b/setup.py
index 690499df23674089be59ad6f3a3f1a7ab07227d5..92f583e58b9120efa90004baa75e57e1e796dfda 100644
--- a/setup.py
+++ b/setup.py
@@ -96,7 +96,7 @@ binary_c_python_api_module = Extension(
         "include", 
     ]
     + binary_c_incdirs
-    + [GSL_DIR] if GSL_DIR else [],
+    + [os.path.join(GSL_DIR,'include')] if GSL_DIR else [],
     libraries=["binary_c"] + binary_c_libs + ["binary_c_api"],
     library_dirs=[
         os.environ["BINARY_C"] + "/src",