diff --git a/var/spack/repos/builtin/packages/7zip/package.py b/var/spack/repos/builtin/packages/7zip/package.py
index 2e9d09bbb9c..123e233ab18 100644
--- a/var/spack/repos/builtin/packages/7zip/package.py
+++ b/var/spack/repos/builtin/packages/7zip/package.py
@@ -75,8 +75,8 @@ def is_64bit(self):
     def build(self, spec, prefix):
         link_type = "1" if "static" in spec.variants["link_type"].value else "0"
         nmake_args = [
-            "PLATFORM=%s" % self.plat_arch,
-            "MY_STATIC_LINK=%s" % link_type,
+            f"PLATFORM={self.plat_arch}",
+            f"MY_STATIC_LINK={link_type}",
             "NEW_COMPILER=1",
         ]
         # 7zips makefile is configured in such as way that if this value is set