diff --git a/var/spack/repos/builtin/packages/openblas/package.py b/var/spack/repos/builtin/packages/openblas/package.py
index b663a3bb48c..daa52348bc5 100644
--- a/var/spack/repos/builtin/packages/openblas/package.py
+++ b/var/spack/repos/builtin/packages/openblas/package.py
@@ -260,6 +260,10 @@ def make_defs(self):
         if '+consistent_fpcsr' in self.spec:
             make_defs += ['CONSISTENT_FPCSR=1']
 
+        # Flang/f18 does not provide ETIME as an intrinsic
+        if self.spec.satisfies('%clang'):
+            make_defs.append('TIMER=INT_CPU_TIME')
+
         # Prevent errors in `as` assembler from newer instructions
         if self.spec.satisfies('%gcc@:4.8.4'):
             make_defs.append('NO_AVX2=1')