--- setup.py
+++ setup.py
@@ -197,7 +197,7 @@
         for file in _LIB_IMAGING:
             files.append(os.path.join("libImaging", file + ".c"))
 
-        libs = []
+        libs = ["m"]
         defs = []
         if feature.jpeg:
             libs.append(feature.jpeg)
@@ -249,7 +249,7 @@
                 libraries=[feature.tcl, feature.tk]))
 
         if os.path.isfile("_imagingmath.c"):
-            exts.append(Extension("_imagingmath", ["_imagingmath.c"]))
+            exts.append(Extension("_imagingmath", ["_imagingmath.c"], libraries=["m"]))
 
         self.extensions[:] = exts