diff --git a/src/normalized.jl b/src/normalized.jl
index 623a3fc..cfc45fe 100644
--- a/src/normalized.jl
+++ b/src/normalized.jl
@@ -22,5 +22,9 @@ end
 function evaluate{T <: QGram}(normalized::Normalized{T}, s1::AbstractString, s2::AbstractString, 
     len1::Integer, len2::Integer)
     distance = evaluate(normalized.dist, s1, s2, len1, len2)
-    return distance / (max(0, len1 - normalized.dist.q + 1) + max(0, len2 - normalized.dist.q + 1))
+    if len1 == normalized.dist.q - 1
+    	return s1 == s2 ? 0.0 : 1.0
+    else 
+    	return distance / (len1 + len2 - 2 * normalized.dist.q + 2)
+    end
 end
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diff --git a/src/qgram.jl b/src/qgram.jl
index 5baa55c..3b49b2d 100644
--- a/src/qgram.jl
+++ b/src/qgram.jl
@@ -116,7 +116,7 @@ function evaluate(dist::Cosine, s1::AbstractString, s2::AbstractString, len1::In
         numerator += v1 * get(bag2.dict, k, 0)
     end
     denominator = sqrt(sumabs2(values(bag1.dict))) * sqrt(sumabs2(values(bag2.dict)))
-    return denominator == 0 ? convert(Float64, 1 - (s1 == s2)) : 1.0 - numerator / denominator
+    return denominator != 0 ? 1.0 - numerator / denominator : s1 == s2 ? 0.0 : 1.0
 end
 
 cosine(s1::AbstractString, s2::AbstractString; q::Integer = 2) = evaluate(Cosine(q), s1::AbstractString, s2::AbstractString)
@@ -152,7 +152,7 @@ function evaluate(dist::Jaccard, s1::AbstractString, s2::AbstractString, len1::I
         end
     end
     denominator = length(set1) + length(set2) - numerator
-    return denominator == 0 ?  convert(Float64, 1 - (s1 == s2)) : 1.0 - numerator / denominator
+    return denominator != 0 ?  1.0 - numerator / denominator : s1 == s2 ? 0.0 : 1.0
 end
 
 jaccard(s1::AbstractString, s2::AbstractString; q::Integer = 2) = evaluate(Jaccard(q), s1::AbstractString, s2::AbstractString)
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