diff --git a/src/math/floorf.rs b/src/math/floorf.rs
index 8699be060..8a63874eb 100644
--- a/src/math/floorf.rs
+++ b/src/math/floorf.rs
@@ -12,7 +12,7 @@ pub fn floorf(x: f32) -> f32 {
         }
     }
     let mut ui = x.to_bits();
-    let e = (((ui >> 23) & 0xff) - 0x7f) as i32;
+    let e = (((ui >> 23) as i32) & 0xff) - 0x7f;
 
     if e >= 23 {
         return x;
@@ -37,3 +37,11 @@ pub fn floorf(x: f32) -> f32 {
     }
     return f32::from_bits(ui);
 }
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn no_overflow() {
+        assert_eq!(super::floorf(0.5), 0.0);
+    }
+}