diff --git a/src/Groups.jl b/src/Groups.jl
index 0934ddb..baf308a 100644
--- a/src/Groups.jl
+++ b/src/Groups.jl
@@ -21,6 +21,7 @@ include("words.jl")
 include("hashing.jl")
 include("freereduce.jl")
 include("arithmetic.jl")
+include("findreplace.jl")
 
 include("FreeGroup.jl")
 include("FPGroups.jl")
@@ -70,189 +71,6 @@ end
     end
 end
 
-###############################################################################
-#
-#   Replacement of symbols / sub-words
-#
-
-issubsymbol(s::GSymbol, t::GSymbol) =
-    s.id == t.id && (0 ≤ s.pow ≤ t.pow || 0 ≥ s.pow ≥ t.pow)
-
-function issubsymbol(s::FreeSymbol, w::GWord, sindex::Integer)
-    @boundscheck 1 ≤ sindex ≤ syllablelength(w) || throw(BoundsError(w, sindex))
-    return issubsymbol(s, syllables(w)[sindex])
-end
-
-function issubword(z::GWord, w::GWord, sindex::Integer)
-    isempty(z) && return true
-    @boundscheck 1 ≤ sindex ≤ syllablelength(w) || throw(BoundsError(w, sindex))
-    n = syllablelength(z)
-    n == 1 && return issubsymbol(first(syllables(z)), syllables(w)[sindex])
-
-    lastindex = sindex + n - 1
-    lastindex > syllablelength(w) && return false
-
-    issubsymbol(first(z), syllables(w)[sindex]) || return false
-    issubsymbol(syllables(z)[end], syllables(w)[lastindex]) || return false
-    for (zidx, widx) in zip(2:n-1, sindex+1:lastindex-1)
-        syllables(z)[zidx] == syllables(w)[widx] || return false
-    end
-    return true
-end
-
-"""doc
-Find the first syllable index k>=i such that Z < syllables(W)[k:k+syllablelength(Z)-1]
-"""
-function findnext(subword::GWord, word::GWord, start::Integer)
-    @boundscheck 1 ≤ start ≤ syllablelength(word) || throw(BoundsError(word, start))
-    isempty(subword) && return start
-    stop = syllablelength(word) - syllablelength(subword) +1
-
-    for idx in start:1:stop
-        issubword(subword, word, idx) && return idx
-    end
-    return nothing
-end
-
-function findnext(s::FreeSymbol, word::GWord, start::Integer)
-    @boundscheck 1 ≤ start ≤ syllablelength(word) || throw(BoundsError(word, start))
-    isone(s) && return start
-    stop = syllablelength(word)
-
-    for idx in start:1:stop
-        issubsymbol(s, word, idx) && return idx
-    end
-    return nothing
-end
-
-function findprev(subword::GWord, word::GWord, start::Integer)
-    @boundscheck 1 ≤ start ≤ syllablelength(word) || throw(BoundsError(word, start))
-    isempty(subword) && return start
-    stop = 1
-
-    for idx in start:-1:1
-        issubword(subword, word, idx) && return idx
-    end
-    return nothing
-end
-
-function findprev(s::FreeSymbol, word::GWord, start::Integer)
-    @boundscheck 1 ≤ start ≤ syllablelength(word) || throw(BoundsError(word, start))
-    isone(s) && return start
-    stop = 1
-
-    for idx in start:-1:stop
-        issubsymbol(s, word, idx) && return idx
-    end
-    return nothing
-end
-
-findfirst(subword::GWord, word::GWord) = findnext(subword, word, 1)
-findlast(subword::GWord, word::GWord) =
-    findprev(subword, word, syllablelength(word)-syllablelength(subword)+1)
-
-function replace!(out::GW, W::GW, lhs_rhs::Pair{GS, T}; count::Integer=typemax(Int)) where
-        {GS<:GSymbol, T<:GWord, GW<:GWord}
-    (count == 0 || isempty(W)) && return W
-    count < 0 && throw(DomainError(count, "`count` must be non-negative."))
-
-    lhs, rhs = lhs_rhs
-
-    sW = syllables(W)
-    sW_idx = 1
-    r = something(findnext(lhs, W, sW_idx), 0)
-
-    sout = syllables(out)
-    resize!(sout, 0)
-    sizehint!(sout, syllablelength(W))
-
-    c = 0
-
-    while !iszero(r)
-        append!(sout, view(sW, sW_idx:r-1))
-        a, b = divrem(sW[r].pow, lhs.pow)
-
-        if b != 0
-            push!(sout, change_pow(sW[r], b))
-        end
-
-        append!(sout, repeat(syllables(rhs), a))
-
-        sW_idx = r+1
-        sW_idx > syllablelength(W) && break
-
-        r = something(findnext(lhs, W, sW_idx), 0)
-        c += 1
-        c == count && break
-    end
-    append!(sout, sW[sW_idx:end])
-    return freereduce!(out)
-end
-
-function replace!(out::GW, W::GW, lhs_rhs::Pair{T, T}; count::Integer=typemax(Int)) where
-    {GW<:GWord, T <: GWord}
-    (count == 0 || isempty(W)) && return W
-    count < 0 && throw(DomainError(count, "`count` must be non-negative."))
-
-    lhs, rhs = lhs_rhs
-    lhs_slen = syllablelength(lhs)
-    lhs_slen == 1 && return replace!(out, W, first(syllables(lhs))=>rhs; count=count)
-
-    sW = syllables(W)
-    sW_idx = 1
-    r = something(findnext(lhs, W, sW_idx), 0)
-
-    sout = syllables(out)
-    resize!(sout, 0)
-    sizehint!(sout, syllablelength(W))
-
-    c = 0
-
-    while !iszero(r)
-        append!(sout, view(sW, sW_idx:r-1))
-
-        exp = sW[r].pow - first(syllables(lhs)).pow
-        if exp != 0
-            push!(sout, change_pow(sW[r], exp))
-        end
-
-        append!(sout, syllables(rhs))
-
-        exp = sW[r+lhs_slen-1].pow - last(syllables(lhs)).pow
-        if exp != 0
-            push!(sout, change_pow(sW[r+lhs_slen-1], exp))
-        end
-
-        sW_idx = r+lhs_slen
-        sW_idx > syllablelength(W) && break
-
-        r = something(findnext(lhs, W, sW_idx), 0)
-        c += 1
-        c == count && break
-    end
-
-    # copy the rest
-    append!(sout, sW[sW_idx:end])
-    return freereduce!(out)
-end
-
-function replace(W::GW, lhs_rhs::Pair{T, T}; count::Integer=typemax(Int)) where
-    {GW<:GWord, T <: GWord}
-    return replace!(one(W), W, lhs_rhs; count=count)
-end
-
-function replace(W::GW, subst_dict::Dict{T,T}) where {GW<:GWord, T<:GWord}
-    out = W
-    for toreplace in reverse!(sort!(collect(keys(subst_dict)), by=length))
-        replacement = subst_dict[toreplace]
-        if length(toreplace) > length(out)
-            continue
-        end
-        out = replace(out, toreplace=>replacement)
-    end
-    return out
-end
-
 ###############################################################################
 #
 #   Misc
diff --git a/src/findreplace.jl b/src/findreplace.jl
new file mode 100644
index 0000000..50fc358
--- /dev/null
+++ b/src/findreplace.jl
@@ -0,0 +1,182 @@
+###############################################################################
+#
+#   Replacement of symbols / sub-words
+#
+
+issubsymbol(s::GSymbol, t::GSymbol) =
+    s.id == t.id && (0 ≤ s.pow ≤ t.pow || 0 ≥ s.pow ≥ t.pow)
+
+function issubsymbol(s::FreeSymbol, w::GWord, sindex::Integer)
+    @boundscheck 1 ≤ sindex ≤ syllablelength(w) || throw(BoundsError(w, sindex))
+    return issubsymbol(s, syllables(w)[sindex])
+end
+
+function issubword(z::GWord, w::GWord, sindex::Integer)
+    isempty(z) && return true
+    @boundscheck 1 ≤ sindex ≤ syllablelength(w) || throw(BoundsError(w, sindex))
+    n = syllablelength(z)
+    n == 1 && return issubsymbol(first(syllables(z)), syllables(w)[sindex])
+
+    lastindex = sindex + n - 1
+    lastindex > syllablelength(w) && return false
+
+    issubsymbol(first(z), syllables(w)[sindex]) || return false
+    issubsymbol(syllables(z)[end], syllables(w)[lastindex]) || return false
+    for (zidx, widx) in zip(2:n-1, sindex+1:lastindex-1)
+        syllables(z)[zidx] == syllables(w)[widx] || return false
+    end
+    return true
+end
+
+"""doc
+Find the first syllable index k>=i such that Z < syllables(W)[k:k+syllablelength(Z)-1]
+"""
+function findnext(subword::GWord, word::GWord, start::Integer)
+    @boundscheck 1 ≤ start ≤ syllablelength(word) || throw(BoundsError(word, start))
+    isempty(subword) && return start
+    stop = syllablelength(word) - syllablelength(subword) +1
+
+    for idx in start:1:stop
+        issubword(subword, word, idx) && return idx
+    end
+    return nothing
+end
+
+function findnext(s::FreeSymbol, word::GWord, start::Integer)
+    @boundscheck 1 ≤ start ≤ syllablelength(word) || throw(BoundsError(word, start))
+    isone(s) && return start
+    stop = syllablelength(word)
+
+    for idx in start:1:stop
+        issubsymbol(s, word, idx) && return idx
+    end
+    return nothing
+end
+
+function findprev(subword::GWord, word::GWord, start::Integer)
+    @boundscheck 1 ≤ start ≤ syllablelength(word) || throw(BoundsError(word, start))
+    isempty(subword) && return start
+    stop = 1
+
+    for idx in start:-1:1
+        issubword(subword, word, idx) && return idx
+    end
+    return nothing
+end
+
+function findprev(s::FreeSymbol, word::GWord, start::Integer)
+    @boundscheck 1 ≤ start ≤ syllablelength(word) || throw(BoundsError(word, start))
+    isone(s) && return start
+    stop = 1
+
+    for idx in start:-1:stop
+        issubsymbol(s, word, idx) && return idx
+    end
+    return nothing
+end
+
+findfirst(subword::GWord, word::GWord) = findnext(subword, word, 1)
+findlast(subword::GWord, word::GWord) =
+    findprev(subword, word, syllablelength(word)-syllablelength(subword)+1)
+
+function replace!(out::GW, W::GW, lhs_rhs::Pair{GS, T}; count::Integer=typemax(Int)) where
+        {GS<:GSymbol, T<:GWord, GW<:GWord}
+    (count == 0 || isempty(W)) && return W
+    count < 0 && throw(DomainError(count, "`count` must be non-negative."))
+
+    lhs, rhs = lhs_rhs
+
+    sW = syllables(W)
+    sW_idx = 1
+    r = something(findnext(lhs, W, sW_idx), 0)
+
+    sout = syllables(out)
+    resize!(sout, 0)
+    sizehint!(sout, syllablelength(W))
+
+    c = 0
+
+    while !iszero(r)
+        append!(sout, view(sW, sW_idx:r-1))
+        a, b = divrem(sW[r].pow, lhs.pow)
+
+        if b != 0
+            push!(sout, change_pow(sW[r], b))
+        end
+
+        append!(sout, repeat(syllables(rhs), a))
+
+        sW_idx = r+1
+        sW_idx > syllablelength(W) && break
+
+        r = something(findnext(lhs, W, sW_idx), 0)
+        c += 1
+        c == count && break
+    end
+    append!(sout, sW[sW_idx:end])
+    return freereduce!(out)
+end
+
+function replace!(out::GW, W::GW, lhs_rhs::Pair{T, T}; count::Integer=typemax(Int)) where
+    {GW<:GWord, T <: GWord}
+    (count == 0 || isempty(W)) && return W
+    count < 0 && throw(DomainError(count, "`count` must be non-negative."))
+
+    lhs, rhs = lhs_rhs
+    lhs_slen = syllablelength(lhs)
+    lhs_slen == 1 && return replace!(out, W, first(syllables(lhs))=>rhs; count=count)
+
+    sW = syllables(W)
+    sW_idx = 1
+    r = something(findnext(lhs, W, sW_idx), 0)
+
+    sout = syllables(out)
+    resize!(sout, 0)
+    sizehint!(sout, syllablelength(W))
+
+    c = 0
+
+    while !iszero(r)
+        append!(sout, view(sW, sW_idx:r-1))
+
+        exp = sW[r].pow - first(syllables(lhs)).pow
+        if exp != 0
+            push!(sout, change_pow(sW[r], exp))
+        end
+
+        append!(sout, syllables(rhs))
+
+        exp = sW[r+lhs_slen-1].pow - last(syllables(lhs)).pow
+        if exp != 0
+            push!(sout, change_pow(sW[r+lhs_slen-1], exp))
+        end
+
+        sW_idx = r+lhs_slen
+        sW_idx > syllablelength(W) && break
+
+        r = something(findnext(lhs, W, sW_idx), 0)
+        c += 1
+        c == count && break
+    end
+
+    # copy the rest
+    append!(sout, sW[sW_idx:end])
+    return freereduce!(out)
+end
+
+function replace(W::GW, lhs_rhs::Pair{T, T}; count::Integer=typemax(Int)) where
+    {GW<:GWord, T <: GWord}
+    return replace!(one(W), W, lhs_rhs; count=count)
+end
+
+function replace(W::GW, subst_dict::Dict{T,T}) where {GW<:GWord, T<:GWord}
+    out = W
+    for toreplace in reverse!(sort!(collect(keys(subst_dict)), by=length))
+        replacement = subst_dict[toreplace]
+        if length(toreplace) > length(out)
+            continue
+        end
+        out = replace(out, toreplace=>replacement)
+    end
+    return out
+end