diff --git a/lib/spack/spack/solver/asp.py b/lib/spack/spack/solver/asp.py
index 712a21b05b4..311b0c47538 100644
--- a/lib/spack/spack/solver/asp.py
+++ b/lib/spack/spack/solver/asp.py
@@ -12,6 +12,7 @@
 import sys
 import time
 import types
+import warnings
 from six import string_types
 
 import archspec.cpu
@@ -1040,7 +1041,9 @@ def _supported_targets(self, compiler_name, compiler_version, targets):
 
         for target in targets:
             try:
-                target.optimization_flags(compiler_name, compiler_version)
+                with warnings.catch_warnings():
+                    warnings.simplefilter("ignore")
+                    target.optimization_flags(compiler_name, compiler_version)
                 supported.append(target)
             except archspec.cpu.UnsupportedMicroarchitecture:
                 continue