diff --git a/res/cases/v1/err-sections-after-custom.wasm b/res/cases/v1/err-sections-after-custom.wasm
new file mode 100644
index 0000000..fb6ec7e
Binary files /dev/null and b/res/cases/v1/err-sections-after-custom.wasm differ
diff --git a/src/elements/module.rs b/src/elements/module.rs
index 394b48c..0e5252b 100644
--- a/src/elements/module.rs
+++ b/src/elements/module.rs
@@ -243,8 +243,8 @@ impl Deserialize for Module {
 						} else if last_section_id == section.id() {
 							return Err(Error::DuplicatedSections(last_section_id));
 						}
+						last_section_id = section.id();
 					}
-					last_section_id = section.id();
 					sections.push(section);
 				}
 			}