diff --git a/luksan/luksan.h b/luksan/luksan.h
index 66b9281b5bb4c5ea06d1589e61b6d14970026632..5161bf5ff8225a96e2574bc23395009dd3e62850 100644
--- a/luksan/luksan.h
+++ b/luksan/luksan.h
@@ -32,6 +32,11 @@ nlopt_result luksan_pnet(int n, nlopt_func f, void *f_data,
 			 int mf,
 			 int mos1, int mos2);
 
+typedef struct {
+     double fl, fu, pl, rl, pu, ru;
+     int mes1, mes2, mes3, mode;
+} ps1l01_state;
+
 /*****************************  internal routines *************************/
 
 /* mssubs.c: */
@@ -88,7 +93,7 @@ void luksan_ps1l01__(double *r__, double *rp,
 		     tolp, double *par1, double *par2, int *kd, int *ld, 
 		     int *nit, int *kit, int *nred, int *mred, int *
 		     maxst, int *iest, int *inits, int *iters, int *kters, 
-		     int *mes, int *isys);
+		     int *mes, int *isys, ps1l01_state *state);
 void luksan_pulsp3__(int *n, int *m, int *mf, 
 		     double *xm, double *gr, double *xo, double *go, 
 		     double *r__, double *po, double *sig, int *iterh, 
diff --git a/luksan/plip.c b/luksan/plip.c
index 8f42b3a4e972c10edaf1fe9170fbaa9e6aa62c68..8bce79ee1d9c134022c96056e984dc562f7b813a 100644
--- a/luksan/plip.c
+++ b/luksan/plip.c
@@ -153,6 +153,7 @@ static void plip_(int *nf, int *nb, double *x, int *
     int iters, irest, inits, kters, maxst;
     double snorm;
     int mtesx, ntesx;
+    ps1l01_state state;
 
 /*     INITIATION */
 
@@ -375,7 +376,8 @@ L11130:
 L11170:
     luksan_ps1l01__(&r__, &rp, f, &fo, &fp, &p, &po, &pp, minf_est, &maxf, &rmin, 
 	    &rmax, &tols, &tolp, &par1, &par2, &kd, &ld, &stat_1->nit, &kit, &
-	    nred, &mred, &maxst, iest, &inits, &iters, &kters, &mes, &isys);
+	    nred, &mred, &maxst, iest, &inits, &iters, &kters, &mes,
+		    &isys, &state);
     if (isys == 0) {
 	goto L11174;
     }
diff --git a/luksan/plis.c b/luksan/plis.c
index 84d4c0a06f4114cacdcaa7c0c5530c29ccf7affb..11d371f209560912a864404b08e6276e47462c47 100644
--- a/luksan/plis.c
+++ b/luksan/plis.c
@@ -144,6 +144,7 @@ static void plis_(int *nf, int *nb, double *x, int *
     int iters, irest, inits, kters, maxst;
     double snorm;
     int mtesx, ntesx;
+    ps1l01_state state;
 
 /*     INITIATION */
 
@@ -382,7 +383,8 @@ L12620:
 L11170:
     luksan_ps1l01__(&r__, &rp, f, &fo, &fp, &p, &po, &pp, minf_est, &maxf, &rmin, 
 	    &rmax, &tols, &tolp, &par1, &par2, &kd, &ld, &stat_1->nit, &kit, &
-	    nred, &mred, &maxst, iest, &inits, &iters, &kters, &mes, &isys);
+	    nred, &mred, &maxst, iest, &inits, &iters, &kters, &mes,
+		    &isys, &state);
     if (isys == 0) {
 	goto L11174;
     }
diff --git a/luksan/pnet.c b/luksan/pnet.c
index bf6192eda12aa10bbc4a83c89457f1c9c2629149..d57461c1d6224de35cd34b3ab8f257bab33bc5a2 100644
--- a/luksan/pnet.c
+++ b/luksan/pnet.c
@@ -172,6 +172,7 @@ static void pnet_(int *nf, int *nb, double *x, int *
     int iters, irest, inits, kters, maxst;
     double snorm;
     int mtesx, ntesx;
+    ps1l01_state state;
 
 /*     INITIATION */
 
@@ -517,7 +518,8 @@ L12560:
 L11060:
     luksan_ps1l01__(&r__, &rp, f, &fo, &fp, &p, &po, &pp, minf_est, &maxf, &rmin, 
 	    &rmax, &tols, &tolp, &par1, &par2, &kd, &ld, &stat_1->nit, &kit, &
-	    nred, &mred, &maxst, iest, &inits, &iters, &kters, &mes, &isys);
+	    nred, &mred, &maxst, iest, &inits, &iters, &kters, &mes,
+		    &isys, &state);
     if (isys == 0) {
 	goto L11064;
     }
diff --git a/luksan/pssubs.c b/luksan/pssubs.c
index 2d3f94869f2d6c411784d76a5ae2ec441b1aaac3..5393d74ffac0f04fa2815ea16a377dc9b34fa074 100644
--- a/luksan/pssubs.c
+++ b/luksan/pssubs.c
@@ -202,6 +202,16 @@ L1:
     return;
 } /* luksan_pnint1__ */
 
+/* save and restore state, replacing old non-reeentrant implementation
+   that used static local variables */
+#define SS(var) state->var = var
+#define SAVE_STATE SS(fl); SS(fu); SS(pl); SS(rl); SS(pu); SS(ru); \
+                   SS(mes1); SS(mes2); SS(mes3); SS(mode)
+#define RS(var) var = state->var
+#define RESTORE_STATE RS(fl); RS(fu); RS(pl); RS(rl); RS(pu); RS(ru); \
+                      RS(mes1); RS(mes2); RS(mes3); RS(mode)
+
+
 /* cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc */
 /* SUBROUTINE PS1L01                ALL SYSTEMS                97/12/01
 * PURPOSE :
@@ -276,20 +286,22 @@ void luksan_ps1l01__(double *r__, double *rp,
 	tolp, double *par1, double *par2, int *kd, int *ld, 
 	int *nit, int *kit, int *nred, int *mred, int *
 	maxst, int *iest, int *inits, int *iters, int *kters, 
-	int *mes, int *isys)
+	int *mes, int *isys, ps1l01_state *state)
 {
     /* System generated locals */
     double d__1, d__2;
 
     /* Local variables */
     unsigned l1, l2, l3, m1, l5, m2, l7, m3;
-    static double fl, fu, pl, rl, pu, ru;
-    static int mes1, mes2, mes3, mode;
+    double fl, fu, pl, rl, pu, ru;
+    int mes1, mes2, mes3, mode;
     int merr;
     static int mtyp;
     int init1;
     double rtemp;
 
+    RESTORE_STATE;
+
     if (*isys == 1) {
 	goto L3;
     }
@@ -363,6 +375,7 @@ L2:
     *kd = 1;
     *ld = -1;
     *isys = 1;
+    SAVE_STATE;
     return;
 L3:
     if (mode == 0) {
@@ -463,6 +476,7 @@ L3:
     goto L2;
 L4:
     *isys = 0;
+    SAVE_STATE;
     return;
 } /* luksan_ps1l01__ */