diff --git a/OpenNL/include/OpenNL/bicgstab.h b/OpenNL/include/OpenNL/bicgstab.h
index 8fae6c727bd..53370b66a72 100644
--- a/OpenNL/include/OpenNL/bicgstab.h
+++ b/OpenNL/include/OpenNL/bicgstab.h
@@ -137,7 +137,8 @@ public:
         while ( rTr>err && its < max_iter) {
             mult(A,d,Ad);
             rTAd=BLAS<Vector>::dot(rT,Ad);
-            assert( ! IsZero(rTAd) );
+            if (IsZero(rTAd))
+                break;                                          // stop if bad conditioning
             alpha=rTh/rTAd;
             BLAS<Vector>::axpy(-alpha,Ad,r);
             BLAS<Vector>::copy(h,s);
@@ -156,8 +157,10 @@ public:
             BLAS<Vector>::axpy(-omega,s,x);
             BLAS<Vector>::copy(s,h);
             BLAS<Vector>::axpy(-omega,t,h);
-            assert( ! IsZero(omega) );
-            assert( ! IsZero(rTh) );
+            if (IsZero(omega))
+                break;                                          // stop if bad conditioning
+            if (IsZero(rTh))
+                break;                                          // stop if bad conditioning
             beta=(alpha/omega)/rTh; rTh=BLAS<Vector>::dot(rT,h); beta*=rTh;
             BLAS<Vector>::scal(beta,d);
             BLAS<Vector>::axpy(1,h,d);
diff --git a/OpenNL/include/OpenNL/conjugate_gradient.h b/OpenNL/include/OpenNL/conjugate_gradient.h
index 88ccc783828..bddc5d7e829 100644
--- a/OpenNL/include/OpenNL/conjugate_gradient.h
+++ b/OpenNL/include/OpenNL/conjugate_gradient.h
@@ -136,11 +136,13 @@ public:
             rho=BLAS<Vector>::dot(p,p);
             sig=BLAS<Vector>::dot(r,p);
             tau=BLAS<Vector>::dot(g,r);
-            assert( ! IsZero(sig) );
+            if (IsZero(sig))
+                break;                                          // stop if bad conditioning
             t=tau/sig;
             BLAS<Vector>::axpy(t,r,x);
             BLAS<Vector>::axpy(-t,p,g);
-            assert( ! IsZero(tau) );
+            if (IsZero(tau))
+                break;                                          // stop if bad conditioning
             gam=(t*t*rho-tau)/tau;
             BLAS<Vector>::scal(gam,r);
             BLAS<Vector>::axpy(1,g,r);