diff --git a/tests/isnan.ispc b/tests/isnan.ispc
new file mode 100644
index 00000000..1cbf928e
--- /dev/null
+++ b/tests/isnan.ispc
@@ -0,0 +1,39 @@
+
+export uniform int width() { return programCount; }
+
+export void f_v(uniform float RET[]) {
+    int errors = 0;
+    for (uniform int i = -2; i <= 2; ++i) {
+        float f = log((float)i);
+
+        if ((i < 0) && (!isnan(f))) errors ++;
+        if ((i >= 0) && isnan(f))   errors ++;
+    }
+
+    for (uniform int i = -2; i <= 2; ++i) {
+        uniform float f = log((uniform float)i);
+        
+        if ((i < 0) && (!isnan(f))) errors ++;
+        if ((i >= 0) && isnan(f))   errors ++;
+    }
+
+    for (uniform int i = -2; i <= 2; ++i) {
+        double f = log((double)i);
+        
+        if ((i < 0) && (!isnan(f))) errors ++;
+        if ((i >= 0) && isnan(f))   errors ++;
+    }
+
+    for (uniform int i = -2; i <= 2; ++i) {
+        uniform double f = log((uniform double)i);
+        
+        if ((i < 0) && (!isnan(f))) errors ++;
+        if ((i >= 0) && isnan(f))   errors ++;
+    }
+
+    RET[programIndex] = errors;
+}
+
+export void result(uniform float RET[]) {
+    RET[programIndex] = 0;
+}