diff --git a/include/lmms_math.h b/include/lmms_math.h
index d89280be2..1e3b530ae 100644
--- a/include/lmms_math.h
+++ b/include/lmms_math.h
@@ -34,7 +34,7 @@
 #include <cmath>
 using namespace std;
 
-#if defined (LMMS_BUILD_WIN32) || defined (LMMS_BUILD_APPLE) 
+#if defined (LMMS_BUILD_WIN32) || defined (LMMS_BUILD_APPLE) || defined(LMMS_BUILD_HAIKU)
 #ifndef isnanf
 #define isnanf(x)	isnan(x)
 #endif