diff --git a/docs/src/crossover.md b/docs/src/crossover.md
index d0524dc..0bb445d 100644
--- a/docs/src/crossover.md
+++ b/docs/src/crossover.md
@@ -76,4 +76,4 @@ Evolutionary.crosstree
 
 [^5]: K. Deep, K. P. Singh, M. L. Kansal, and C. Mohan, "A real coded  genetic algorithm for solving integer and mixed integer optimization problems.", Appl. Math. Comput. 212, 505-518, 2009
 
-[^6]  K. Deb, R. B. Agrawal, "Simulated Binary Crossover for Continuous Search Space", Complex Syst., 9., 1995
+[^6]: K. Deb, R. B. Agrawal, "Simulated Binary Crossover for Continuous Search Space", Complex Syst., 9., 1995
diff --git a/docs/src/mutation.md b/docs/src/mutation.md
index 6124796..9825770 100644
--- a/docs/src/mutation.md
+++ b/docs/src/mutation.md
@@ -92,4 +92,4 @@ shrink
 
 [^8]: P. J. Angeline, "An investigation into the sensitivity of genetic programming to the frequency of leaf selection during subtree crossover", Genetic Programming 1996: Proceedings of the First Annual Conference, 21–29, 1996.
 
-[^9]  K. Deb, R. B. Agrawal, "Simulated Binary Crossover for Continuous Search Space", Complex Syst., 9., 1995
\ No newline at end of file
+[^9]: K. Deb, R. B. Agrawal, "Simulated Binary Crossover for Continuous Search Space", Complex Syst., 9., 1995
\ No newline at end of file
diff --git a/src/mutations.jl b/src/mutations.jl
index 911c8d2..b9ce105 100644
--- a/src/mutations.jl
+++ b/src/mutations.jl
@@ -250,7 +250,7 @@ function PLM(Δ::Vector, η=2; pm::Real=NaN) # index of distribution p
     end
     return mutation
 end
-PLM(lower::Vector, upper::Vector, η::Real = 2; pm::Real=NaN) = PLM(upper-lower, η; pm)
+PLM(lower::Vector, upper::Vector, η::Real = 2; pm::Real=NaN) = PLM(upper-lower, η; pm=pm)
 
 
 # Combinatorial mutations (applicable to binary vectors)