diff --git a/tool/microkit/src/sdf.rs b/tool/microkit/src/sdf.rs
index 17b5adba..b800c77e 100644
--- a/tool/microkit/src/sdf.rs
+++ b/tool/microkit/src/sdf.rs
@@ -977,17 +977,6 @@ impl ProtectionDomain {
                     }
                 }
                 "setvar" => {
-                    match config.arch {
-                        Arch::Aarch64 | Arch::Riscv64 => {}
-                        Arch::X86_64 => {
-                            return Err(value_error(
-                                xml_sdf,
-                                node,
-                                "setvar with 'region_paddr' for MR without a specified paddr is unsupported on x86_64".to_string(),
-                            ));
-                        }
-                    };
-
                     check_attributes(xml_sdf, &child, &["symbol", "region_paddr"])?;
                     let symbol = checked_lookup(xml_sdf, &child, "symbol")?.to_string();
                     let region = checked_lookup(xml_sdf, &child, "region_paddr")?.to_string();
@@ -2006,8 +1995,19 @@ pub fn parse(filename: &str, xml: &str, config: &Config) -> Result<SystemDescrip
         if mr_names_with_setvar_paddr.contains(&mr.name)
             && mr.phys_addr == SysMemoryRegionPaddr::Unspecified
         {
-            // The actual allocation is done by another part of the tool.
-            mr.phys_addr = SysMemoryRegionPaddr::ToolAllocated(None);
+            match config.arch {
+                Arch::Aarch64 | Arch::Riscv64 => {
+                    // The actual allocation is done by another part of the tool.
+                    mr.phys_addr = SysMemoryRegionPaddr::ToolAllocated(None);
+                }
+                Arch::X86_64 => {
+                    return Err(format!(
+                        "Error: setvar with 'region_paddr' for MR without a specified paddr is unsupported on x86-64 @ '{}' {}",
+                        mr.name,
+                        loc_string(&xml_sdf, mr.text_pos.unwrap()),
+                    ));
+                }
+            };
         }
     }
 
diff --git a/tool/microkit/tests/sdf/pd_setvar_no_paddr.system b/tool/microkit/tests/sdf/pd_setvar_no_paddr.system
new file mode 100644
index 00000000..77af3c97
--- /dev/null
+++ b/tool/microkit/tests/sdf/pd_setvar_no_paddr.system
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+ Copyright 2026, UNSW
+
+ SPDX-License-Identifier: BSD-2-Clause
+-->
+<system>
+    <memory_region name="test_mr" size="0x1000" />
+    <protection_domain name="test">
+        <program_image path="test.elf" />
+
+        <setvar region_paddr="test_mr" symbol="test" />
+    </protection_domain>
+</system>
diff --git a/tool/microkit/tests/sdf/pd_setvar_with_paddr.system b/tool/microkit/tests/sdf/pd_setvar_with_paddr.system
new file mode 100644
index 00000000..da3be915
--- /dev/null
+++ b/tool/microkit/tests/sdf/pd_setvar_with_paddr.system
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+ Copyright 2026, UNSW
+
+ SPDX-License-Identifier: BSD-2-Clause
+-->
+<system>
+    <memory_region name="test_mr" size="0x1000" phys_addr="0x1_000_000" />
+    <protection_domain name="test">
+        <program_image path="test.elf" />
+
+        <setvar region_paddr="test_mr" symbol="test" />
+    </protection_domain>
+</system>
diff --git a/tool/microkit/tests/test.rs b/tool/microkit/tests/test.rs
index 2ae153b2..c4859f67 100644
--- a/tool/microkit/tests/test.rs
+++ b/tool/microkit/tests/test.rs
@@ -58,6 +58,20 @@ const DEFAULT_X86_64_KERNEL_CONFIG: sel4::Config = sel4::Config {
     normal_regions: None,
 };
 
+fn check_success(kernel_config: &sel4::Config, test_name: &str) {
+    let mut path = std::path::PathBuf::from(env!("CARGO_MANIFEST_DIR"));
+    path.push("tests/sdf/");
+    path.push(test_name);
+    let sdf = std::fs::read_to_string(path).unwrap();
+    let parse = sdf::parse(test_name, &sdf, kernel_config);
+
+    if let Err(ref e) = parse {
+        eprintln!("Expected no error, instead got:\n{e}")
+    }
+
+    assert!(parse.is_ok());
+}
+
 fn check_error(kernel_config: &sel4::Config, test_name: &str, expected_err: &str) {
     let mut path = std::path::PathBuf::from(env!("CARGO_MANIFEST_DIR"));
     path.push("tests/sdf/");
@@ -254,6 +268,20 @@ mod protection_domain {
         )
     }
 
+    #[test]
+    fn test_setvar_paddr_with_paddr() {
+        check_success(&DEFAULT_X86_64_KERNEL_CONFIG, "pd_setvar_with_paddr.system")
+    }
+
+    #[test]
+    fn test_setvar_paddr_no_paddr() {
+        check_error(
+            &DEFAULT_X86_64_KERNEL_CONFIG,
+            "pd_setvar_no_paddr.system",
+            "Error: setvar with 'region_paddr' for MR without a specified paddr is unsupported on x86-64 @",
+        )
+    }
+
     #[test]
     fn test_duplicate_program_image() {
         check_error(