diff --git a/lslopt/lslbasefuncs.py b/lslopt/lslbasefuncs.py
index f9bdccf..2a987e2 100644
--- a/lslopt/lslbasefuncs.py
+++ b/lslopt/lslbasefuncs.py
@@ -669,8 +669,6 @@ def div(a, b, f32=True):
         if b == 0:
             raise ELSLMathError
         if ta in (int, float):
-            if math.isnan(a): # NaN/anything gives math error
-                raise ELSLMathError
             if ta == int and tb == int:
                 # special case
                 if a == -2147483648 and b == -1:
@@ -679,7 +677,10 @@ def div(a, b, f32=True):
                     # signs differ - Python rounds towards -inf, we need rounding towards 0
                     return - a//-b # that's -(a//-b) not (-a)//-b
                 return a//b
-            return F32(ff(a)/ff(b), f32)
+            ret = F32(ff(a)/ff(b), f32)
+            if math.isnan(res): # A NaN result gives a math error.
+                raise ELSLMathError
+            return ret
         if ta == Vector:
             a = v2f(a)
             b = ff(b)
diff --git a/testfuncs.py b/testfuncs.py
index 2a3920e..8eb17fe 100644
--- a/testfuncs.py
+++ b/testfuncs.py
@@ -493,6 +493,9 @@ def do_tests():
 
     shouldexcept('div(1.0, 0.0)', ELSLMathError)
     shouldexcept('div(1, 0)', ELSLMathError)
+    shouldexcept('div(NaN, 1)', ELSLMathError)
+    shouldexcept('div(1, NaN)', ELSLMathError)
+    shouldexcept('div(F32(1e40), F32(1e40))', ELSLMathError)
     shouldexcept('zstr("blah")', ELSLInvalidType)
     test(r'zstr(Key(u"xy\0zzy"))', Key(u'xy'))
     test('typecast(Infinity, unicode)', u'Infinity')