diff --git a/src/include/pzdefs.h b/src/include/pzdefs.h
index a73cd101d..591b0e840 100644
--- a/src/include/pzdefs.h
+++ b/src/include/pzdefs.h
@@ -4,6 +4,7 @@
     /* structure used to describe an PZ analysis to be performed */
 
 #include "jobdefs.h"
+#include <math.h>
 #include "complex.h"
 
 typedef struct strial {