diff --git a/fixed_wide/src/fixed.rs b/fixed_wide/src/fixed.rs
index 985d530..ac972bb 100644
--- a/fixed_wide/src/fixed.rs
+++ b/fixed_wide/src/fixed.rs
@@ -173,7 +173,7 @@ macro_rules! impl_into_float {
 					msb_offset<<($mantissa_bits-1)
 				};
 				let digits=unsigned.digits();
-				let digit_index=most_significant_bit>>DIGIT_SHIFT;
+				let digit_index=most_significant_bit.saturating_sub(1)>>DIGIT_SHIFT;
 				let digit=digits[digit_index as usize];
 				//How many bits does the mantissa take from this digit
 				let take_bits=most_significant_bit-(digit_index<<DIGIT_SHIFT);