diff --git a/base/array.jl b/base/array.jl
index 85296b4d94f21..e50c1a9c806ad 100644
--- a/base/array.jl
+++ b/base/array.jl
@@ -2325,7 +2325,7 @@ findall(testf::Function, A) = collect(first(p) for p in pairs(A) if testf(last(p
 
 # Broadcasting is much faster for small testf, and computing
 # integer indices from logical index using findall has a negligible cost
-findall(testf::Function, A::AbstractArray) = findall(testf.(A))
+findall(testf::F, A::AbstractArray) where {F<:Function} = findall(testf.(A))
 
 """
     findall(A)