diff --git a/src/basicfuns.jl b/src/basicfuns.jl
index 576ccea..e741abe 100644
--- a/src/basicfuns.jl
+++ b/src/basicfuns.jl
@@ -13,7 +13,7 @@ julia> StatsFuns.xlogx(0)
 """
 function xlogx(x)
     result = x * log(x)
-    ifelse(x > zero(x), result, zero(result))
+    ifelse(iszero(x), zero(result), result)
 end
 
 """
@@ -23,7 +23,7 @@ Return `x * log(y)` for `y > 0` with correct limit at `x = 0`.
 """
 function xlogy(x, y)
     result = x * log(y)
-    ifelse(x > zero(x), result, zero(result))
+    ifelse(iszero(x), zero(result), result)
 end
 
 # The following bounds are precomputed versions of the following abstract
diff --git a/test/basicfuns.jl b/test/basicfuns.jl
index d4f6b9c..bfbd639 100644
--- a/test/basicfuns.jl
+++ b/test/basicfuns.jl
@@ -3,9 +3,11 @@ using StatsFuns, Test
 @testset "xlogx & xlogy" begin
     @test iszero(xlogx(0))
     @test xlogx(2) ≈ 2.0 * log(2.0)
+    @test_throws DomainError xlogx(-1)
 
     @test iszero(xlogy(0, 1))
     @test xlogy(2, 3) ≈ 2.0 * log(3.0)
+    @test_throws DomainError xlogy(1, -1)
 end
 
 @testset "logistic & logit" begin
@@ -94,7 +96,7 @@ end
             @test logsumexp(arguments) ≡ result
         end
     end
-    
+
     @test isnan(logsubexp(Inf, Inf))
     @test isnan(logsubexp(-Inf, -Inf))
     @test logsubexp(Inf, 9.0) ≡ Inf