diff --git a/makefile b/makefile
index 55ff4a8..9f9b04b 100644
--- a/makefile
+++ b/makefile
@@ -1,4 +1,4 @@
-CFLAGS=-ggdb3 -O2 -Wno-pointer-sign -Wno-parentheses
+CFLAGS=-ggdb3 -O2 -Wno-pointer-sign -Wno-parentheses -Wextra -Werror -Wsign-compare -Wwrite-strings
 ifeq ($(shell uname),Linux)
 LDFLAGS=-fPIC -shared
 QLIBDIR=l64
diff --git a/py.c b/py.c
index 8aca695..e20ca1e 100644
--- a/py.c
+++ b/py.c
@@ -6,7 +6,7 @@ ZV*t1(){R PyEval_SaveThread();}ZV t0(V*t){PyEval_RestoreThread(t);}ZP M;ZV**N;ZP
 ZP p1(P p){Py_IncRef(p);R p;}ZV p0(P p){Py_DecRef(p);}ZI pt(P p,P t){P u=PyObject_Type(p);I f;f=(u==t||PyType_IsSubtype(u,t));p0(u);R f;}
 ZP pg(K x){R(P)(kK(x)[1]);}ZV pd(K x){I g=g1();p0(pg(x));g0(g);}ZK kfp(P p){K x=knk(2,pd,p);R xt=112,x;}ZI pq(K x){R xt==112&&xn==2&&*kK(x)==(K)pd;}
 ZK kfg(P p){R PyCapsule_GetPointer(p,"k");}ZV kfd(P p){r0(kfg(p));}ZP pfk(K x){R PyCapsule_New(r1(x),"k",kfd);}
-ZK prr(S s){ZC __thread b[4096];J n=sizeof(b)-1;P t,v,d,a;*b=0;strncat(b,s,n);PyErr_Fetch(&t,&v,&d);if(t){PyErr_NormalizeException(&t,&v,&d);
+ZK prr(S s){Z __thread C b[4096];J n=sizeof(b)-1;P t,v,d,a;*b=0;strncat(b,s,n);PyErr_Fetch(&t,&v,&d);if(t){PyErr_NormalizeException(&t,&v,&d);
  strncat(strncat(b,": ",n),PyUnicode_AsUTF8AndSize(a=PyObject_Str(v),0),n);p0(a);p0(t);p0(v);p0(d);}R krr(b);}ZK prg(S s,I g){K r=prr(s);g0(g);R r;}
 
 ZK ko(P);ZK cf;//k from python
diff --git a/py.h b/py.h
index 9ede435..737bbb8 100644
--- a/py.h
+++ b/py.h
@@ -116,3 +116,9 @@ ZI pyn(V**v){
 #define X(r,n,a,i) U(n=(T##n(*)a)v[i])
  NF
  R 1;}
+#ifdef __clang__
+#pragma clang diagnostic ignored "-Wincompatible-pointer-types-discards-qualifiers"
+#pragma clang diagnostic ignored "-Wunused-parameter"
+#elif __GNUC__
+#pragma GCC diagnostic ignored "-Wdiscarded-qualifiers"
+#endif