diff --git a/var/spack/repos/builtin/packages/py-numpy/package.py b/var/spack/repos/builtin/packages/py-numpy/package.py
index 02fc694df90..83554f55618 100644
--- a/var/spack/repos/builtin/packages/py-numpy/package.py
+++ b/var/spack/repos/builtin/packages/py-numpy/package.py
@@ -161,6 +161,7 @@ class PyNumpy(PythonPackage):
     # meson.build
     # https://docs.scipy.org/doc/scipy/dev/toolchain.html#compilers
     conflicts("%gcc@:8.3", when="@1.26:", msg="NumPy requires GCC >= 8.4")
+    conflicts("%gcc@:6.4", when="@1.23:", msg="NumPy requires GCC >= 6.5")
     conflicts("%gcc@:4.7", msg="NumPy requires GCC >= 4.8")
     conflicts(
         "%msvc@:19.19",