diff --git a/lib/codegen.gi b/lib/codegen.gi
index d42f4e8..f2e3387 100644
--- a/lib/codegen.gi
+++ b/lib/codegen.gi
@@ -111,7 +111,7 @@ end);
 ##Create a linear code from a list of Codeword generators
 LinearCodeByGenerators := function(F, gens)
 
-    local V, M, i, j, row;
+    local V, M;
     V:= Objectify( NewType( FamilyObj( gens ),
                             IsLeftModule and
                 IsLinearCodeRep and IsCodeDefaultRep ),
@@ -128,7 +128,7 @@ LinearCodeByGenerators := function(F, gens)
         od;
         Append(M, [row]);
     od;
-    SetGeneratorMat(V, M ) ;
+    SetGeneratorMat(V, M);
     return V;
 
 end;
diff --git a/lib/codeops.gi b/lib/codeops.gi
index 3e8dc1f..652ba82 100644
--- a/lib/codeops.gi
+++ b/lib/codeops.gi
@@ -691,7 +691,7 @@ function(C)
     local majority,G0, Gp, Gpt, Gt, L, k, i, j, dimMat, Grstr, J, d1, arrayd1, Combo, rows, row, rowSum, G, F, zero, AClosestVec, s, p, num;
     F:=LeftActingDomain(C);
     if F<>GF(2) then Print("Code must be binary. Quitting. \n"); return(0); fi;
-    G := GeneratorMat(C);
+    G := MutableCopyMatrix(GeneratorMat(C));
     if (IsInStandardForm(G)=false) then
         PutStandardForm(G);
     fi;
@@ -757,7 +757,7 @@ function(C,p,num)
     # p = 5 seems to be optimal
     # num = 8 seems to be optimal
     local majority,G0, Gp, Gpt, Gt, L, k, i, j, dimMat, Grstr, J, d1, arrayd1, Combo, rows, row, rowSum, G, F, zero, AClosestVec, s;
-    G := GeneratorMat(C);
+    G := MutableCopyMatrix(GeneratorMat(C));
     if (IsInStandardForm(G)=false) then
         PutStandardForm(G);
     fi;
diff --git a/lib/matrices.gi b/lib/matrices.gi
index fcb1629..d3388b9 100644
--- a/lib/matrices.gi
+++ b/lib/matrices.gi
@@ -636,7 +636,7 @@ InstallOtherMethod(PutStandardForm, "method for matrix and Field", true,
     [IsMatrix, IsField], 0,
 function(M, F)
 local mat, perm, k, i, j, d ;
- mat := MutableCopyMatrix(M);
+ mat:=MutableCopyMatrix(M);
  d := Length(mat[1]);
  TriangulizeMat(mat);
  perm := ();