diff --git a/lib/spack/spack/spec.py b/lib/spack/spack/spec.py
index 4159d18b740..0c6a49dd4c1 100644
--- a/lib/spack/spack/spec.py
+++ b/lib/spack/spack/spec.py
@@ -1872,7 +1872,7 @@ def write(s, c):
                 fmt += 's'
 
                 if c == '_':
-                    if name = self.name if self.name else ''
+                    name = self.name if self.name else ''
                     out.write(fmt % name)
                 elif c == '.':
                     out.write(fmt % self.fullname)