diff --git a/var/spack/repos/builtin/packages/fenics-dolfinx/package.py b/var/spack/repos/builtin/packages/fenics-dolfinx/package.py
index 25e1e2b3676..519198c6d82 100644
--- a/var/spack/repos/builtin/packages/fenics-dolfinx/package.py
+++ b/var/spack/repos/builtin/packages/fenics-dolfinx/package.py
@@ -30,6 +30,7 @@ class FenicsDolfinx(CMakePackage):
         multi=True,
     )
 
+    # HDF5 dependency requires C in CMake
     depends_on("c", type="build")
     depends_on("cxx", type="build")  # generated
 
@@ -40,7 +41,9 @@ class FenicsDolfinx(CMakePackage):
 
     variant("slepc", default=False, description="slepc support")
     variant("adios2", default=False, description="adios2 support")
+    variant("petsc", default=False, description="PETSc support")
 
+    depends_on("petsc", when="+slepc")
     depends_on("cmake@3.21:", when="@0.9:", type="build")
     depends_on("cmake@3.19:", when="@:0.8", type="build")
     depends_on("pkgconfig", type="build")
@@ -50,7 +53,7 @@ class FenicsDolfinx(CMakePackage):
     depends_on("pugixml")
     depends_on("spdlog", when="@0.9:")
 
-    depends_on("petsc+mpi+shared")
+    depends_on("petsc+mpi+shared", when="+petsc")
     depends_on("slepc", when="+slepc")
 
     depends_on("adios2@2.8.1:+mpi", when="@0.9: +adios2")
@@ -76,6 +79,7 @@ class FenicsDolfinx(CMakePackage):
     def cmake_args(self):
         return [
             self.define("DOLFINX_SKIP_BUILD_TESTS", True),
+            self.define_from_variant("DOLFINX_ENABLE_PETSC", "petsc"),
             self.define_from_variant("DOLFINX_ENABLE_SLEPC", "slepc"),
             self.define_from_variant("DOLFINX_ENABLE_ADIOS2", "adios2"),
             self.define("DOLFINX_UFCX_PYTHON", False),