diff --git a/src/librustc/diagnostics.rs b/src/librustc/diagnostics.rs
index 6d94e1d725938f2b9c3930087b085b0dc26b7001..2878ff5e2846e4f9ad8a776d7758d1a927925e2a 100644
--- a/src/librustc/diagnostics.rs
+++ b/src/librustc/diagnostics.rs
@@ -1694,12 +1694,12 @@ fn main() {
 https://doc.rust-lang.org/book/closures.html
 "##,
 
-E0579: r##"
+E0580: r##"
 The `main` function was incorrectly declared.
 
 Erroneous code example:
 
-```compile_fail,E0579
+```compile_fail,E0580
 fn main() -> i32 { // error: main function has wrong type
     0
 }
diff --git a/src/librustc/infer/error_reporting.rs b/src/librustc/infer/error_reporting.rs
index 2bed8148b9f8c8a4e5feb0319fa5218b414efd68..d859a8b44db0c2af41723e3889427d3042cede3c 100644
--- a/src/librustc/infer/error_reporting.rs
+++ b/src/librustc/infer/error_reporting.rs
@@ -631,7 +631,7 @@ pub fn report_and_explain_type_error(&self,
                 struct_span_err!(self.tcx.sess, span, E0317, "{}", failure_str)
             }
             ObligationCauseCode::MainFunctionType => {
-                struct_span_err!(self.tcx.sess, span, E0579, "{}", failure_str)
+                struct_span_err!(self.tcx.sess, span, E0580, "{}", failure_str)
             }
             _ => {
                 struct_span_err!(self.tcx.sess, span, E0308, "{}", failure_str)
diff --git a/src/test/compile-fail/E0579.rs b/src/test/compile-fail/E0580.rs
similarity index 92%
rename from src/test/compile-fail/E0579.rs
rename to src/test/compile-fail/E0580.rs
index beb6c792fa18ac9d3fd5a33589b3d4857112f3fe..a2ef7da78a84366ed2a9fcfbbf6ebfdf631909cb 100644
--- a/src/test/compile-fail/E0579.rs
+++ b/src/test/compile-fail/E0580.rs
@@ -8,4 +8,4 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-fn main() -> i32 { 0 } //~ ERROR E0579
+fn main() -> i32 { 0 } //~ ERROR E0580
diff --git a/src/test/compile-fail/bad-main.rs b/src/test/compile-fail/bad-main.rs
index 6cd033da4bd711e7d7eac9381f8df1eeeb363eea..b73b4a6af6e89e8fdcd3e29012ab6000c85ac2bb 100644
--- a/src/test/compile-fail/bad-main.rs
+++ b/src/test/compile-fail/bad-main.rs
@@ -8,4 +8,4 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-fn main(x: isize) { } //~ ERROR: main function has wrong type [E0579]
+fn main(x: isize) { } //~ ERROR: main function has wrong type [E0580]
diff --git a/src/test/compile-fail/extern-main-fn.rs b/src/test/compile-fail/extern-main-fn.rs
index 479b3e532c6b3baec316c7375388c2a3c53367da..d9bdb4ecd04777a7384fc3b08c274130a5368f57 100644
--- a/src/test/compile-fail/extern-main-fn.rs
+++ b/src/test/compile-fail/extern-main-fn.rs
@@ -8,4 +8,4 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-extern fn main() {} //~ ERROR: main function has wrong type [E0579]
+extern fn main() {} //~ ERROR: main function has wrong type [E0580]
diff --git a/src/test/compile-fail/main-wrong-type-2.rs b/src/test/compile-fail/main-wrong-type-2.rs
index da1455403c2e3d29c2e4558cecf0032618be0388..9d74d1a90493bd8c8f08532c63685824df467c5d 100644
--- a/src/test/compile-fail/main-wrong-type-2.rs
+++ b/src/test/compile-fail/main-wrong-type-2.rs
@@ -9,6 +9,6 @@
 // except according to those terms.
 
 fn main() -> char {
-//~^ ERROR: main function has wrong type [E0579]
+//~^ ERROR: main function has wrong type [E0580]
     ' '
 }
diff --git a/src/test/compile-fail/main-wrong-type.rs b/src/test/compile-fail/main-wrong-type.rs
index dc51777503569c381db611b03db84a0f9ec0f29c..402cd3a2d31b6f2dbeeab22336c924a7361a3d60 100644
--- a/src/test/compile-fail/main-wrong-type.rs
+++ b/src/test/compile-fail/main-wrong-type.rs
@@ -14,5 +14,5 @@ struct S {
 }
 
 fn main(foo: S) {
-//~^ ERROR: main function has wrong type [E0579]
+//~^ ERROR: main function has wrong type [E0580]
 }