diff --git a/Python/pymath.c b/Python/pymath.c
index 2e049be..eb06eb2 100644
--- a/Python/pymath.c
+++ b/Python/pymath.c
@@ -69,6 +69,19 @@
 }
 #endif /* HAVE_COPYSIGN */
 
+#ifndef HAVE_ROUND
+double
+round(double x)
+{
+    double absx, y;
+    absx = fabs(x);
+    y = floor(absx);
+    if (absx - y >= 0.5)
+        y += 1.0;
+    return copysign(y, x);
+}
+#endif /* HAVE_ROUND */
+
 #ifndef HAVE_LOG1P
 #include <float.h>