diff --git a/CHANGELOG.md b/CHANGELOG.md
index eee698cc..ce99715b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 ## [UNRELEASED]
+### Added
+* Improved error message when encoding LongDNA from byte-like objects
 
 ## [3.1.0]
 ### Added
diff --git a/src/longsequences/copying.jl b/src/longsequences/copying.jl
index f939a811..b98e0360 100644
--- a/src/longsequences/copying.jl
+++ b/src/longsequences/copying.jl
@@ -152,9 +152,19 @@ end
 # This is used to effectively scan an array of UInt8 for invalid bytes, when one is detected
 @noinline function throw_encode_error(A::Alphabet, src::AbstractArray{UInt8}, soff::Integer)
     for i in 1:div(64, bits_per_symbol(A))
-        sym = src[soff+i-1]
-        ascii_encode(A, sym) & 0x80 == 0x80 && error("Cannot encode $(repr(sym)) to $A")
+        index = soff + i - 1
+        sym = src[index]
+        if ascii_encode(A, sym) & 0x80 == 0x80
+            # If byte is a printable char, also display it
+            repr_char = if sym in UInt8('\a'):UInt8('\r') || sym in UInt8(' '):UInt8('~')
+                " (char '$(Char(sym))')"
+            else
+                ""
+            end
+            error("Cannot encode byte $(repr(sym))$(repr_char) at index $(index) to $A")
+        end
     end
+    @assert false "Expected error in encoding"
 end
 
 @inline function encode_chunk(A::Alphabet, src::AbstractArray{UInt8}, soff::Integer, N::Integer)
diff --git a/test/longsequences/basics.jl b/test/longsequences/basics.jl
index 02af359e..d0c71705 100644
--- a/test/longsequences/basics.jl
+++ b/test/longsequences/basics.jl
@@ -24,6 +24,15 @@
     @test LongSequence(SimpleSeq("AUCGU")) isa LongRNA{2}
     @test LongSequence(SimpleSeq("AUCGU")) == LongRNA{2}("AUCGU")
     LongDNA{4}(LongRNA{4}("AUCGUA")) == LongDNA{4}("ATCGTA")
+
+    # Displays a nice error when constructed from strings substrings
+    # and bytearrays on encoding error
+    @static if VERSION >= v"1.8"
+        malformed = "ACWpNS"
+        @test_throws "Cannot encode byte $(repr(UInt8('p'))) (char 'p') at index 4 to BioSequences.DNAAlphabet{4}" LongDNA{4}(malformed)
+        malformed = "AGCUGUAGUCGGUAUAUAGGCGCGCUCGAUGAUGAUGCGUGCUGCUATDNANCUG"
+        @test_throws "Cannot encode byte $(repr(UInt8('T'))) (char 'T') at index $(length(malformed) - 7) to BioSequences.RNAAlphabet{2}" LongRNA{2}(malformed)
+    end
 end
 
 @testset "Copy sequence" begin