diff --git a/cranelift/src/libcretonne/ir/instructions.rs b/cranelift/src/libcretonne/ir/instructions.rs
index 4087e246d5..9d5c59eb7d 100644
--- a/cranelift/src/libcretonne/ir/instructions.rs
+++ b/cranelift/src/libcretonne/ir/instructions.rs
@@ -54,16 +54,6 @@ impl Opcode {
     }
 }
 
-// A primitive hash function for matching opcodes.
-// Must match `meta/constant_hash.py`.
-fn simple_hash(s: &str) -> u32 {
-    let mut h: u32 = 5381;
-    for c in s.chars() {
-        h = (h ^ c as u32).wrapping_add(h.rotate_right(6));
-    }
-    h
-}
-
 // This trait really belongs in libreader where it is used by the .cton file parser, but since it
 // critically depends on the `opcode_name()` function which is needed here anyway, it lives in this
 // module. This also saves us from runing the build script twice to generate code for the two
@@ -73,6 +63,7 @@ impl FromStr for Opcode {
 
     /// Parse an Opcode name from a string.
     fn from_str(s: &str) -> Result<Opcode, &'static str> {
+        use simple_hash::simple_hash;
         let tlen = OPCODE_HASH_TABLE.len();
         assert!(tlen.is_power_of_two());
         let mut idx = simple_hash(s) as usize;
diff --git a/cranelift/src/libcretonne/lib.rs b/cranelift/src/libcretonne/lib.rs
index 766c33abcf..a8cd09ab8d 100644
--- a/cranelift/src/libcretonne/lib.rs
+++ b/cranelift/src/libcretonne/lib.rs
@@ -15,4 +15,6 @@ pub mod dominator_tree;
 pub mod entity_map;
 pub mod settings;
 
+mod simple_hash;
+
 #[cfg(test)]pub mod test_utils;
diff --git a/cranelift/src/libcretonne/simple_hash.rs b/cranelift/src/libcretonne/simple_hash.rs
new file mode 100644
index 0000000000..99cd80015c
--- /dev/null
+++ b/cranelift/src/libcretonne/simple_hash.rs
@@ -0,0 +1,21 @@
+/// A primitive hash function for matching opcodes.
+/// Must match `meta/constant_hash.py`.
+pub fn simple_hash(s: &str) -> u32 {
+    let mut h: u32 = 5381;
+    for c in s.chars() {
+        h = (h ^ c as u32).wrapping_add(h.rotate_right(6));
+    }
+    h
+}
+
+#[cfg(test)]
+mod tests {
+    use super::simple_hash;
+
+    #[test]
+    fn basic() {
+        // c.f. meta/constant_hash.py tests.
+        assert_eq!(simple_hash("Hello"), 0x2fa70c01);
+        assert_eq!(simple_hash("world"), 0x5b0c31d5);
+    }
+}