--- a/src/druntime/src/core/stdc/math.d
+++ b/src/druntime/src/core/stdc/math.d
@@ -493,7 +493,7 @@ version( FreeBSD )
     int     ilogbl(real x) { return ilogb(x); }
     real    ldexpl(real x, int exp) { return ldexp(x, exp); }
     real    logbl(real x) { return logb(x); }
-    //real    modfl(real value, real *iptr); // nontrivial conversion
+    real    modfl(real value, real *iptr);
     real    scalbnl(real x, int n) { return scalbn(x, n); }
     real    scalblnl(real x, c_long n) { return scalbln(x, n); }
     real    fabsl(real x) { return fabs(x); }