diff --git a/configure.ac b/configure.ac
index ce025798e4..46a4982726 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2246,10 +2246,6 @@ fi
     AC_MSG_RESULT(yes)
 
     RUST_FEATURES=""
-    AS_VERSION_COMPARE([$rustc_version], [1.38.0],
-        [],
-	[RUST_FEATURES="$RUST_FEATURES function-macro"],
-	[RUST_FEATURES="$RUST_FEATURES function-macro"])
 
     rust_vendor_comment="# "
     have_rust_vendor="no"
diff --git a/rust/Cargo.toml.in b/rust/Cargo.toml.in
index 3f484c339e..6febd4c532 100644
--- a/rust/Cargo.toml.in
+++ b/rust/Cargo.toml.in
@@ -20,7 +20,6 @@ lua_int8 = ["lua"]
 strict = []
 debug = []
 debug-validate = []
-function-macro = []
 
 [dependencies]
 nom = "~5.1.2"
diff --git a/rust/src/log.rs b/rust/src/log.rs
index b61c6cddaf..83c1dc357b 100644
--- a/rust/src/log.rs
+++ b/rust/src/log.rs
@@ -84,7 +84,6 @@ pub fn sclog(level: Level, file: &str, line: u32, function: &str,
 // This macro has been borrowed from https://github.com/popzxc/stdext-rs, which
 // is released under the MIT license as there is currently no macro in Rust
 // to provide the function name.
-#[cfg(feature = "function-macro")]
 #[macro_export(local_inner_macros)]
 macro_rules!function {
     () => {{
@@ -98,14 +97,6 @@ macro_rules!function {
     }}
 }
 
-// Rust versions less than 1.38 can not use the above macro, so keep the old
-// macro around for a while.
-#[cfg(not(feature = "function-macro"))]
-#[macro_export(local_inner_macros)]
-macro_rules!function {
-    () => {{ "<rust>" }}
-}
-
 #[macro_export]
 macro_rules!do_log {
     ($level:expr, $code:expr, $($arg:tt)*) => {