diff --git a/src/data/number.rs b/src/data/number.rs
index 90c34c7..5a41b68 100644
--- a/src/data/number.rs
+++ b/src/data/number.rs
@@ -218,15 +218,8 @@ impl IntLayout {
     }
 
     /// Returns whether a `usize`-value fits the layout dimensions.
-    ///
-    /// # Panics
-    ///
-    /// Panics on platforms where usize is less than `u64`
     pub fn fits_usize(self, value: usize) -> bool {
-        (self.bytes() <= 8 && value > u64::MAX as usize)
-            || (self.bytes() <= 4 && value > u32::MAX as usize)
-            || (self.bytes() <= 2 && value > u16::MAX as usize)
-            || (self.bytes() <= 1 && value > u8::MAX as usize)
+        self.bits() >= (usize::BITS - value.leading_zeros()) as u16
     }
 }
 
diff --git a/src/isa/instr.rs b/src/isa/instr.rs
index af15117..aa23224 100644
--- a/src/isa/instr.rs
+++ b/src/isa/instr.rs
@@ -644,18 +644,15 @@ pub enum BytesOp {
     ///
     /// If the string register is empty, or destination register can't fit the length, sets `st0`
     /// to `false` and destination register to `None`.
-    #[display("len     {0},{1}{2}")]
+    #[display("len     {1}{2},{0}")]
     Len(/** `s` register index */ RegS, RegA, Reg32),
 
     /// Count number of byte occurrences from the `a8` register within the string and stores that
     /// value into destination `a16` register.
     ///
-    /// If the string register is empty, or destination register can't fit the length, sets `st0`
-    /// to `false` and destination register to `None`.
-    ///
-    /// If the source byte value register is uninitialized, sets destination register to `None` and
-    /// `st0` to `false`.
-    #[display("cnt     {0},a8{1},a16{2}")]
+    /// If the string register is empty, or the source byte value register is uninitialized, sets
+    /// `st0` to `false` and destination register to `None`.
+    #[display("cnt     a16{2},{0},a8{1}")]
     Cnt(
         /** `s` register index */ RegS,
         /** `a8` register with the byte value */ Reg16,
@@ -669,15 +666,15 @@ pub enum BytesOp {
     Eq(RegS, RegS),
 
     /// Compute offset and length of the `n`th fragment shared between two strings ("conjoint
-    /// fragment"), putting it to the destination `u16` registers. If strings have no conjoint
+    /// fragment"), putting it to the destination `a16` registers. If strings have no conjoint
     /// fragment sets destination to `None`.
-    #[display("con     {0},{1},a16{2},u16{3},u16{4}")]
+    #[display("con     a16{3},a16{4},{0},{1},a16{2}")]
     Con(
         /** First source string register */ RegS,
         /** Second source string register */ RegS,
         /** Index of the conjoint fragment to match */ Reg32,
-        /** `u16` register index to save the offset of the conjoint fragment */ Reg32,
-        /** `u16` register index to save the length of the conjoint fragment */ Reg32,
+        /** `a16` register index to save the offset of the conjoint fragment */ Reg32,
+        /** `a16` register index to save the length of the conjoint fragment */ Reg32,
     ),
 
     /// Count number of occurrences of one string within another putting result to `a16[1]`,
diff --git a/src/library/cursor.rs b/src/library/cursor.rs
index b891f38..1b8f6cb 100644
--- a/src/library/cursor.rs
+++ b/src/library/cursor.rs
@@ -184,7 +184,11 @@ where
         // We write the value only if the value is not yet present in the data segment
         let len = bytes.len();
         let offset = self.data.as_ref().len();
-        if let Some(offset) = self.data.as_ref().windows(len).position(|window| window == bytes) {
+        if len == 0 {
+            Ok(offset as u16)
+        } else if let Some(offset) =
+            self.data.as_ref().windows(len).position(|window| window == bytes)
+        {
             Ok(offset as u16)
         } else if offset + len > DATA_SEGMENT_MAX_LEN {
             Err(WriteError::DataNotFittingSegment)