diff --git a/c_tools/hod/halo_concentration.c b/c_tools/hod/halo_concentration.c
index 71f0f9b..238a878 100644
--- a/c_tools/hod/halo_concentration.c
+++ b/c_tools/hod/halo_concentration.c
@@ -78,7 +78,7 @@ double halo_concentration(double m)
 
 double cvir_model(double mass)
 {
-  double cvir,z_coll,zbrent(),rad;
+  double cvir,z_coll,rad;
   double k=3.12;
   double f=0.001;
  
diff --git a/c_tools/hod/hod_functions.c b/c_tools/hod/hod_functions.c
index e7003d5..e929e7b 100644
--- a/c_tools/hod/hod_functions.c
+++ b/c_tools/hod/hod_functions.c
@@ -542,7 +542,7 @@ double func_central_density(double m)
  */
 double number_weighted_halo_mass()
 {
-  double funcxx1();
+  double funcxx1(double);
   return(qromo(funcxx1,log(HOD.M_low),log(HOD.M_max),midpnt)/GALAXY_DENSITY);
 }
 double funcxx1(double m)
@@ -556,7 +556,7 @@ double funcxx1(double m)
  */
 double number_weighted_central_mass()
 {
-  double funcxx2();
+  double funcxx2(double);
   return(qromo(funcxx2,log(HOD.M_low),log(HOD.M_max),midpnt)/
 	 qromo(func_central_density,log(HOD.M_low),log(HOD.M_max),midpnt));
 }
diff --git a/c_tools/hod/xi_matter.c b/c_tools/hod/xi_matter.c
index 2bec7b4..c597073 100644
--- a/c_tools/hod/xi_matter.c
+++ b/c_tools/hod/xi_matter.c
@@ -32,7 +32,7 @@ double xi_interp(double r)
   static int flag=0,prev_cosmo=0;
   static double *x,*y,*y2;
   int n=30,i,j;
-  double a,xi_int(),rhi=95,rlo=0.1,dlogr,klo,s1,s2,tolerance=1.0e-6;
+  double a,rhi=95,rlo=0.1,dlogr,klo,s1,s2,tolerance=1.0e-6;
 
   if(!flag || RESET_COSMOLOGY!=prev_cosmo)
     {
@@ -99,7 +99,7 @@ double xi_linear_interp(double r)
   static double *x,*y,*y2;
   int n=100,i;
   double a,rlo=0.1,rhi=150,dlogr,klo;
-  double xi_linear_int();
+  double xi_linear_int(double);
 
   if(!flag || RESET_COSMOLOGY!=prev_cosmo)
     {
diff --git a/c_tools/hod/zbrent.c b/c_tools/hod/zbrent.c
index 122ff23..efe263d 100644
--- a/c_tools/hod/zbrent.c
+++ b/c_tools/hod/zbrent.c
@@ -8,7 +8,6 @@ double zbrent(double (*func)(double), double x1,double x2, double tol)
 	int iter;
 	double a=x1,b=x2,c,d,e,min1,min2;
 	double fa=(*func)(a),fb=(*func)(b),fc,p,q,r,s,tol1,xm;
-	void nrerror();
 
 	if (fb*fa > 0.0) 
 	  {