diff --git a/var/spack/repos/builtin/packages/ipopt/package.py b/var/spack/repos/builtin/packages/ipopt/package.py
index 43879c2cad..da8f798908 100644
--- a/var/spack/repos/builtin/packages/ipopt/package.py
+++ b/var/spack/repos/builtin/packages/ipopt/package.py
@@ -78,7 +78,7 @@ def configure_args(self):
         lapack_lib = spec['lapack'].libs.ld_flags
 
         args = [
-            "--prefix=%s" % prefix,
+            "--prefix=%s" % self.prefix,
             "--with-mumps-incdir=%s" % mumps_dir.include,
             "--with-mumps-lib=%s" % mumps_libcmd,
             "--enable-shared",