diff --git a/REAPERDenoiser b/REAPERDenoiser
index aaea6a4..f98458a 100644
--- a/REAPERDenoiser
+++ b/REAPERDenoiser
@@ -114,7 +114,7 @@ function store_noise_profile(buffer) global(SIZE, noiseBuffer) local(index, norm
 
 // calculate an attenuation given the yNorm, and nNorm, and kSquared to approximate sNorm
 function denoise(yNorm, nNorm, kSquared) (
-  yNorm / (yNorm + kSquared * nNorm);
+  yNorm > 0 ? yNorm / (yNorm + kSquared * nNorm);
 );
 
 // helpful functions to get/set the right sample given an index
@@ -306,6 +306,15 @@ function sum_first_pdc_samples(s0val, s1val) (
 	);
 );
 
+//DEBUGPRINT("TEST_denoise_0_yNorm\n");
+assert_equal_exact(0, denoise(0, 0, 0));
+
+//DEBUGPRINT("TEST_denoise_really_small_yNorm\n");
+assert_equal_exact(1, denoise(2^-140, 0, 0));
+
+//DEBUGPRINT("TEST_denoise_really_small_yNorm_and_nNorm\n");
+assert_equal_exact(0.5, denoise(2^-140, 2^-140, 1));
+
 //DEBUGPRINT("SAMPLE_1_1_STRESS_TEST\n");
 // spl0=1 spl1=1 for many samples
 sum_first_pdc_samples(1, 1);
diff --git a/testing_defines.eel2 b/testing_defines.eel2
index cb0e252..1e0b7b9 100644
--- a/testing_defines.eel2
+++ b/testing_defines.eel2
@@ -1,8 +1,16 @@
 
 // Helper functions to check for positive infinity, negative infinity, and nan
-function is_pos_inf(x) (x ==  1/0);
-function is_neg_inf(x) (x == -1/0);
-function is_nan(x) (x != x;);
+function is_pos_inf(x) (
+	(x * 2 == x) && x > 0;
+);
+function is_neg_inf(x) (
+	is_pos_inf(-x);
+);
+function is_nan(x) local(z1, z2) (
+	z2 = x;
+	z1 = x + 1;
+	z2 == 0 && z1 == 0;
+);
 
 function assert_equal_exact(expected, actual, message) global(failed_asserts, successful_asserts) (
 	is_nan(expected) && is_nan(actual) ? successful_asserts += 1 :
@@ -62,6 +70,35 @@ function test_summary() global(failed_asserts successful_asserts) local(total) (
 	)
 );
 
+/*
+pif = 0;
+pif = 1/pif;
+nif = 0;
+nif = -1/nif;
+lg = 2^64;
+
+printf("z/z=%g, pif=%g, nif=%g\n", z/z, pif, nif);
+
+assert_true( is_pos_inf(pif),  " +1/0 is +inf");
+assert_false(is_neg_inf(pif),  " +1/0 is -inf");
+assert_false(    is_nan(pif),  " +1/0 is  nan");
+assert_false(is_pos_inf(nif),  " -1/0 is +inf");
+assert_true( is_neg_inf(nif),  " -1/0 is -inf");
+assert_false(    is_nan(nif),  " -1/0 is  nan");
+assert_false(is_pos_inf(z/z),  "  z/z is +inf");
+assert_false(is_neg_inf(z/z),  "  z/z is -inf");
+assert_true(     is_nan(z/z),  "  z/z is  nan");
+assert_false(is_pos_inf(  0),  "   0 is +inf");
+assert_false(is_neg_inf(  0),  "   0 is -inf");
+assert_false(    is_nan(  0),  "   0 is  nan");
+assert_false(is_pos_inf( lg), " 2^64 is +inf");
+assert_false(is_neg_inf( lg), " 2^64 is -inf");
+assert_false(    is_nan( lg), " 2^64 is  nan");
+assert_false(is_pos_inf(-lg), "-2^64 is +inf");
+assert_false(is_neg_inf(-lg), "-2^64 is -inf");
+assert_false(    is_nan(-lg), "-2^64 is  nan");
+*/
+
 // drop in for spl(channel)
 // function spl(channel) (
 // 	0 == channel ? spl0 :