diff --git a/cfg/std.cfg b/cfg/std.cfg
index dd0ce0ef5..935680316 100644
--- a/cfg/std.cfg
+++ b/cfg/std.cfg
@@ -1825,6 +1825,7 @@
     </arg>
     <arg nr="2" direction="in">
       <not-uninit/>
+      <valid>!0.0</valid>
     </arg>
   </function>
   <!-- float fmodf(float x, float y); -->
@@ -1839,6 +1840,7 @@
     </arg>
     <arg nr="2" direction="in">
       <not-uninit/>
+      <valid>!0.0</valid>
     </arg>
   </function>
   <!-- long double fmodl(long double x, long double y); -->
@@ -1853,6 +1855,7 @@
     </arg>
     <arg nr="2" direction="in">
       <not-uninit/>
+      <valid>!0.0</valid>
     </arg>
   </function>
   <!-- FILE * fopen(const char *filename, const char* mode); -->