diff --git a/base/array.jl b/base/array.jl
index 3dbaa5957e885..aa0042429075c 100644
--- a/base/array.jl
+++ b/base/array.jl
@@ -1992,6 +1992,19 @@ function findall(A)
     end
     collect(first(p) for p in _pairs(A) if last(p) != 0)
 end
+# Allocating result upfront is faster (possible only when collection can be iterated twice)
+function findall(A::AbstractArray{Bool})
+    n = count(A)
+    I = Vector{eltype(keys(A))}(uninitialized, n)
+    cnt = 1
+    for (i,a) in pairs(A)
+        if a
+            I[cnt] = i
+            cnt += 1
+        end
+    end
+    I
+end
 
 findall(x::Bool) = x ? [1] : Vector{Int}()
 findall(testf::Function, x::Number) = testf(x) ? [1] : Vector{Int}()
diff --git a/test/arrayops.jl b/test/arrayops.jl
index 101c465037000..df224959f76c6 100644
--- a/test/arrayops.jl
+++ b/test/arrayops.jl
@@ -506,6 +506,19 @@ end
     @test findlast(!iszero, g3) == CartesianIndex(9, 2)
     @test findfirst(equalto(2), g3) === nothing
     @test findlast(equalto(2), g3) === nothing
+
+    g4 = (x for x in [true, false, true, false])
+    @test findall(g4) == [1, 3]
+    @test findfirst(g4) == 1
+    @test findlast(g4) == 3
+
+    g5 = (x for x in [true false; true false])
+    @test findall(g5) == findall(collect(g5))
+    @test findfirst(g5) == CartesianIndex(1, 1)
+    @test findlast(g5) == CartesianIndex(2, 1)
+
+    @test findfirst(x for x in Bool[]) === nothing
+    @test findlast(x for x in Bool[]) === nothing
 end
 
 @testset "findmin findmax argmin argmax" begin