diff --git a/TIGLViewer/src/main.cpp b/TIGLViewer/src/main.cpp
index 30ca26705..8d3afed9d 100644
--- a/TIGLViewer/src/main.cpp
+++ b/TIGLViewer/src/main.cpp
@@ -49,9 +49,11 @@ int main(int argc, char *argv[])
     }
 #endif
 
-#ifdef __linux__
+#if defined __linux__
     // we need to set us locale as we use "." for decimal point
     putenv("LC_NUMERIC=C");
+#elif defined __APPLE__
+    setlocale(LC_NUMERIC, "C");
 #endif
 
     int retval = parseArguments(app.arguments());