diff --git a/src/obj/relocations.rs b/src/obj/relocations.rs
index 1bc38389..0ce3b7b4 100644
--- a/src/obj/relocations.rs
+++ b/src/obj/relocations.rs
@@ -22,6 +22,22 @@ pub enum ObjRelocKind {
     PpcEmbSda21,
 }
 
+impl ObjRelocKind {
+    /// Bits of the target word that the linker overwrites when applying this
+    /// relocation.
+    pub fn value_mask(self) -> u32 {
+        match self {
+            ObjRelocKind::Absolute => !0,
+            ObjRelocKind::PpcAddr16Hi | ObjRelocKind::PpcAddr16Ha | ObjRelocKind::PpcAddr16Lo => {
+                0xFFFF
+            }
+            ObjRelocKind::PpcRel24 => 0x3FFFFFC,
+            ObjRelocKind::PpcRel14 => 0xFFFC,
+            ObjRelocKind::PpcEmbSda21 => 0x1FFFFF,
+        }
+    }
+}
+
 impl Serialize for ObjRelocKind {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where S: serde::Serializer {
diff --git a/src/util/signatures.rs b/src/util/signatures.rs
index 51c628e7..0e4e75db 100644
--- a/src/util/signatures.rs
+++ b/src/util/signatures.rs
@@ -332,30 +332,9 @@ pub fn generate_signature(
                     }
                     btree_map::Entry::Occupied(e) => *e.get(),
                 };
-                match reloc.kind {
-                    ObjRelocKind::Absolute => {
-                        *ins = 0;
-                        *pat = 0;
-                    }
-                    ObjRelocKind::PpcAddr16Hi
-                    | ObjRelocKind::PpcAddr16Ha
-                    | ObjRelocKind::PpcAddr16Lo => {
-                        *ins &= !0xFFFF;
-                        *pat = !0xFFFF;
-                    }
-                    ObjRelocKind::PpcRel24 => {
-                        *ins &= !0x3FFFFFC;
-                        *pat = !0x3FFFFFC;
-                    }
-                    ObjRelocKind::PpcRel14 => {
-                        *ins &= !0xFFFC;
-                        *pat = !0xFFFC;
-                    }
-                    ObjRelocKind::PpcEmbSda21 => {
-                        *ins &= !0x1FFFFF;
-                        *pat = !0x1FFFFF;
-                    }
-                }
+                let mask = !reloc.kind.value_mask();
+                *ins &= mask;
+                *pat = mask;
                 out_relocs.push(OutReloc {
                     offset: addr - (symbol.address as u32),
                     kind: reloc.kind,