diff --git a/pyscf/lib/ao2mo/nr_ao2mo.c b/pyscf/lib/ao2mo/nr_ao2mo.c
index 8fc2a29b06..6debe48ef6 100644
--- a/pyscf/lib/ao2mo/nr_ao2mo.c
+++ b/pyscf/lib/ao2mo/nr_ao2mo.c
@@ -17,6 +17,7 @@
  */
 
 #include <stdlib.h>
+#include <stdio.h>
 #include <math.h>
 #include <assert.h>
 //#define NDEBUG
@@ -1223,7 +1224,11 @@ void AO2MOnr_e1_drv(int (*intor)(), void (*fill)(), void (*ftrans)(), int (*fmmm
 {
         int nao = ao_loc[nbas];
         double *eri_ao = malloc(sizeof(double) * nao*nao*nkl*ncomp);
-        assert(eri_ao);
+        if (eri_ao == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in AO2MOnr_e1_drv\n",
+                        sizeof(double) * nao*nao*nkl*ncomp);
+                exit(1);
+        }
         AO2MOnr_e1fill_drv(intor, fill, eri_ao, klsh_start, klsh_count,
                            nkl, ncomp, ao_loc, cintopt, vhfopt,
                            atm, natm, bas, nbas, env);
diff --git a/pyscf/lib/ao2mo/nrr_ao2mo.c b/pyscf/lib/ao2mo/nrr_ao2mo.c
index 84c7c43548..a283db0d27 100644
--- a/pyscf/lib/ao2mo/nrr_ao2mo.c
+++ b/pyscf/lib/ao2mo/nrr_ao2mo.c
@@ -18,6 +18,7 @@
  */
 
 #include <stdlib.h>
+#include <stdio.h>
 #include <complex.h>
 #include <math.h>
 #include <assert.h>
@@ -237,7 +238,11 @@ void AO2MOnrr_e1_drv(int (*intor)(), void (*fill)(),
 
 
         double *eri_ao = malloc(sizeof(double)* nao*nao*nkl*ncomp);
-        assert(eri_ao);
+        if (eri_ao == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in AO2MOnrr_e1_drv\n",
+                        sizeof(double) * nao*nao*nkl*ncomp);
+                exit(1);
+        }
         int ish, kl;
         int (*fprescreen)();
         if (vhfopt) {
diff --git a/pyscf/lib/ao2mo/r_ao2mo.c b/pyscf/lib/ao2mo/r_ao2mo.c
index f7afa4052c..6ad924efab 100644
--- a/pyscf/lib/ao2mo/r_ao2mo.c
+++ b/pyscf/lib/ao2mo/r_ao2mo.c
@@ -17,6 +17,7 @@
  */
 
 #include <stdlib.h>
+#include <stdio.h>
 #include <complex.h>
 #include <math.h>
 #include <assert.h>
@@ -833,7 +834,11 @@ void AO2MOr_e1_drv(int (*intor)(), void (*fill)(),
 
         double complex *eri_ao = malloc(sizeof(double complex)
                                         * nao*nao*nkl*ncomp);
-        assert(eri_ao);
+        if (eri_ao == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in AO2MOr_e1_drv\n",
+                        sizeof(double complex) * nao*nao*nkl*ncomp);
+                exit(1);
+        }
         int ish, kl;
         int (*fprescreen)();
         if (vhfopt != NULL) {
diff --git a/pyscf/lib/cc/ccsd_t.c b/pyscf/lib/cc/ccsd_t.c
index 24a3cf6692..927b32032d 100644
--- a/pyscf/lib/cc/ccsd_t.c
+++ b/pyscf/lib/cc/ccsd_t.c
@@ -17,6 +17,7 @@
  */
 
 #include <stdlib.h>
+#include <stdio.h>
 #include <complex.h>
 #include "config.h"
 #include "np_helper/np_helper.h"
@@ -393,11 +394,16 @@ void CCsd_t_contract(double *e_tot,
         _make_permute_indices(permute_idx, nocc);
 #pragma omp parallel default(none) \
         shared(njobs, nocc, nvir, mo_energy, t1T, t2T, nirrep, o_ir_loc, \
-               v_ir_loc, oo_ir_loc, orbsym, vooo, fvo, jobs, e_tot, permute_idx)
+               v_ir_loc, oo_ir_loc, orbsym, vooo, fvo, jobs, e_tot, permute_idx, stderr)
 {
         int a, b, c;
         size_t k;
         double *cache1 = malloc(sizeof(double) * (nocc*nocc*nocc*3+2));
+        if (cache1 == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in CCsd_t_contract\n",
+                        sizeof(double) * nocc*nocc*nocc*3);
+                exit(1);
+        }
         double *t1Thalf = malloc(sizeof(double) * nvir*nocc * 2);
         double *fvohalf = t1Thalf + nvir*nocc;
         for (k = 0; k < nvir*nocc; k++) {
@@ -443,11 +449,16 @@ void QCIsd_t_contract(double *e_tot,
         _make_permute_indices(permute_idx, nocc);
 #pragma omp parallel default(none) \
         shared(njobs, nocc, nvir, mo_energy, t1T, t2T, nirrep, o_ir_loc, \
-               v_ir_loc, oo_ir_loc, orbsym, vooo, fvo, jobs, e_tot, permute_idx)
+               v_ir_loc, oo_ir_loc, orbsym, vooo, fvo, jobs, e_tot, permute_idx, stderr)
 {
         int a, b, c;
         size_t k;
         double *cache1 = malloc(sizeof(double) * (nocc*nocc*nocc*3+2));
+        if (cache1 == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in QCIsd_t_contract\n",
+                        sizeof(double) * nocc*nocc*nocc*3);
+                exit(1);
+        }
         double *t1Thalf = malloc(sizeof(double) * nvir*nocc * 2);
         double *fvohalf = t1Thalf + nvir*nocc;
         for (k = 0; k < nvir*nocc; k++) {
@@ -619,11 +630,16 @@ void CCsd_t_zcontract(double complex *e_tot,
 
 #pragma omp parallel default(none) \
         shared(njobs, nocc, nvir, mo_energy, t1T, t2T, nirrep, o_ir_loc, \
-               v_ir_loc, oo_ir_loc, orbsym, vooo, fvo, jobs, e_tot, permute_idx)
+               v_ir_loc, oo_ir_loc, orbsym, vooo, fvo, jobs, e_tot, permute_idx, stderr)
 {
         int a, b, c;
         size_t k;
         double complex *cache1 = malloc(sizeof(double complex) * (nocc*nocc*nocc*3+2));
+        if (cache1 == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in CCsd_t_zcontract\n",
+                        sizeof(double complex) * nocc*nocc*nocc*3);
+                exit(1);
+        }
         double complex *t1Thalf = malloc(sizeof(double complex) * nvir*nocc * 2);
         double complex *fvohalf = t1Thalf + nvir*nocc;
         for (k = 0; k < nvir*nocc; k++) {
@@ -672,11 +688,16 @@ void QCIsd_t_zcontract(double complex *e_tot,
 
 #pragma omp parallel default(none) \
         shared(njobs, nocc, nvir, mo_energy, t1T, t2T, nirrep, o_ir_loc, \
-               v_ir_loc, oo_ir_loc, orbsym, vooo, fvo, jobs, e_tot, permute_idx)
+               v_ir_loc, oo_ir_loc, orbsym, vooo, fvo, jobs, e_tot, permute_idx, stderr)
 {
         int a, b, c;
         size_t k;
         double complex *cache1 = malloc(sizeof(double complex) * (nocc*nocc*nocc*3+2));
+        if (cache1 == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in QCIsd_t_zcontract\n",
+                        sizeof(double complex) * nocc*nocc*nocc*3);
+                exit(1);
+        }
         double complex *t1Thalf = malloc(sizeof(double complex) * nvir*nocc * 2);
         double complex *fvohalf = t1Thalf + nvir*nocc;
         for (k = 0; k < nvir*nocc; k++) {
@@ -853,11 +874,16 @@ void MPICCsd_t_contract(double *e_tot, double *mo_energy, double *t1T,
 
 #pragma omp parallel default(none) \
         shared(njobs, nocc, nvir, mo_energy, t1T, fvo, jobs, e_tot, slices, \
-               data_ptrs, permute_idx)
+               data_ptrs, permute_idx, stderr)
 {
         int a, b, c;
         size_t k;
         double *cache1 = malloc(sizeof(double) * (nocc*nocc*nocc*3+2));
+        if (cache1 == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in MPICCsd_t_contract\n",
+                        sizeof(double) * nocc*nocc*nocc*3);
+                exit(1);
+        }
         double *t1Thalf = malloc(sizeof(double) * nvir*nocc * 2);
         double *fvohalf = t1Thalf + nvir*nocc;
         for (k = 0; k < nvir*nocc; k++) {
@@ -1081,11 +1107,16 @@ void CCsd_zcontract_t3T(double complex *t3Tw, double complex *t3Tv, double *mo_e
 
 #pragma omp parallel default(none) \
         shared(njobs, nocc, nvir, nkpts, t3Tw, t3Tv, mo_offset, mo_energy, t1T, fvo, jobs, slices, \
-               data_ptrs, permute_idx)
+               data_ptrs, permute_idx, stderr)
 {
         int a, b, c;
         size_t k;
         complex double *cache1 = malloc(sizeof(double complex) * (nocc*nocc*nocc*3+2));
+        if (cache1 == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in CCsd_zcontract_t3T\n",
+                        sizeof(double complex) * nocc*nocc*nocc*3);
+                exit(1);
+        }
         complex double *t1Thalf = malloc(sizeof(double complex) * nkpts*nvir*nocc*2);
         complex double *fvohalf = t1Thalf + nkpts*nvir*nocc;
         for (k = 0; k < nkpts*nvir*nocc; k++) {
diff --git a/pyscf/lib/cc/uccsd_t.c b/pyscf/lib/cc/uccsd_t.c
index 9bfd981794..82886e9e10 100644
--- a/pyscf/lib/cc/uccsd_t.c
+++ b/pyscf/lib/cc/uccsd_t.c
@@ -17,6 +17,7 @@
  */
 
 #include <stdlib.h>
+#include <stdio.h>
 #include "config.h"
 #include "np_helper/np_helper.h"
 #include "vhf/fblas.h"
@@ -301,11 +302,16 @@ void CCuccsd_t_aaa(double complex *e_tot,
 #pragma omp parallel default(none) \
         shared(njobs, nocc, nvir, mo_energy, t1T, t2T, nirrep, o_ir_loc, \
                v_ir_loc, oo_ir_loc, orbsym, vooo, fvohalf, jobs, e_tot, \
-               permute_idx)
+               permute_idx, stderr)
 {
         int a, b, c;
         size_t k;
         double *cache1 = malloc(sizeof(double) * (nocc*nocc*nocc*3+2));
+        if (cache1 == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in CCuccsd_t_aaa\n",
+                        sizeof(double) * nocc*nocc*nocc*3);
+                exit(1);
+        }
         double e = 0;
 #pragma omp for schedule (dynamic, 4)
         for (k = 0; k < njobs; k++) {
@@ -544,12 +550,17 @@ void CCuccsd_t_baa(double complex *e_tot,
                 t1aT, t1bT, t2aaT, t2abT};
 
 #pragma omp parallel default(none) \
-        shared(njobs, nocca, noccb, nvira, nvirb, vs_ts, jobs, e_tot)
+        shared(njobs, nocca, noccb, nvira, nvirb, vs_ts, jobs, e_tot, stderr)
 {
         int a, b, c;
         size_t k;
         double *cache1 = malloc(sizeof(double) * (noccb*nocca*nocca*5+1 +
                                                   nocca*2+noccb*2));
+        if (cache1 == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in CCuccsd_t_baa\n",
+                        sizeof(double) * noccb*nocca*nocca*5);
+                exit(1);
+        }
         double e = 0;
 #pragma omp for schedule (dynamic, 4)
         for (k = 0; k < njobs; k++) {
@@ -697,12 +708,17 @@ void CCuccsd_t_zaaa(double complex *e_tot,
 #pragma omp parallel default(none) \
         shared(njobs, nocc, nvir, mo_energy, t1T, t2T, nirrep, o_ir_loc, \
                v_ir_loc, oo_ir_loc, orbsym, vooo, fvohalf, jobs, e_tot, \
-               permute_idx)
+               permute_idx, stderr)
 {
         int a, b, c;
         size_t k;
         double complex *cache1 = malloc(sizeof(double complex) *
                                         (nocc*nocc*nocc*3+2));
+        if (cache1 == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in CCuccsd_t_zaaa\n",
+                        sizeof(double complex) * nocc*nocc*nocc*3);
+                exit(1);
+        }
         double complex e = 0;
 #pragma omp for schedule (dynamic, 4)
         for (k = 0; k < njobs; k++) {
@@ -900,13 +916,18 @@ void CCuccsd_t_zbaa(double complex *e_tot,
                 t1aT, t1bT, t2aaT, t2abT};
 
 #pragma omp parallel default(none) \
-        shared(njobs, nocca, noccb, nvira, nvirb, vs_ts, jobs, e_tot)
+        shared(njobs, nocca, noccb, nvira, nvirb, vs_ts, jobs, e_tot, stderr)
 {
         int a, b, c;
         size_t k;
         double complex *cache1 = malloc(sizeof(double complex) *
                                         (noccb*nocca*nocca*5+1 +
                                          nocca*2+noccb*2));
+        if (cache1 == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in CCuccsd_t_zbaa\n",
+                        sizeof(double complex) * noccb*nocca*nocca*5);
+                exit(1);
+        }
         double complex e = 0;
 #pragma omp for schedule (dynamic, 4)
         for (k = 0; k < njobs; k++) {
diff --git a/pyscf/lib/gto/fill_r_4c.c b/pyscf/lib/gto/fill_r_4c.c
index b9e9db4dec..eb1ad81906 100644
--- a/pyscf/lib/gto/fill_r_4c.c
+++ b/pyscf/lib/gto/fill_r_4c.c
@@ -87,6 +87,11 @@ void GTOr4c_drv(int (*intor)(), void (*fill)(), int (*prescreen)(),
 {
         int ish, jsh, ij;
         double *buf = malloc(sizeof(double) * cache_size);
+        if (buf == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in GTOr4c_drv\n",
+                        sizeof(double) * cache_size);
+                exit(1);
+        }
 #pragma omp for schedule(dynamic)
         for (ij = 0; ij < nish*njsh; ij++) {
                 ish = ij / njsh;
diff --git a/pyscf/lib/vhf/nr_sgx_direct.c b/pyscf/lib/vhf/nr_sgx_direct.c
index 4ae821dde2..3df47fca26 100644
--- a/pyscf/lib/vhf/nr_sgx_direct.c
+++ b/pyscf/lib/vhf/nr_sgx_direct.c
@@ -351,6 +351,11 @@ void SGXsetnr_direct_scf_dm(CVHFOpt *opt, double *dm, int nset, int *ao_loc,
                 free(opt->dm_cond);
         }
         opt->dm_cond = (double *)malloc(sizeof(double) * nbas*ngrids);
+        if (opt->dm_cond == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in SGXsetnr_direct_scf_dm\n",
+                        sizeof(double) * nbas*ngrids);
+                exit(1);
+        }
         // nbas in the input arguments may different to opt->nbas.
         // Use opt->nbas because it is used in the prescreen function
         memset(opt->dm_cond, 0, sizeof(double)*nbas*ngrids);
diff --git a/pyscf/lib/vhf/optimizer.c b/pyscf/lib/vhf/optimizer.c
index 9c339a5ac1..0a0161884d 100644
--- a/pyscf/lib/vhf/optimizer.c
+++ b/pyscf/lib/vhf/optimizer.c
@@ -393,6 +393,11 @@ void CVHFsetnr_direct_scf(CVHFOpt *opt, int (*intor)(), CINTOpt *cintopt,
         // Use opt->nbas because it is used in the prescreen function
         nbas = opt->nbas;
         opt->q_cond = (double *)malloc(sizeof(double) * nbas*nbas);
+        if (opt->q_cond == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in CVHFsetnr_direct_scf\n",
+                        sizeof(double) * nbas*nbas);
+                exit(1);
+        }
         CVHFset_int2e_q_cond(intor, cintopt, opt->q_cond, ao_loc,
                              atm, natm, bas, nbas, env);
 }
@@ -522,6 +527,11 @@ void CVHFsetnr_direct_scf_dm(CVHFOpt *opt, double *dm, int nset, int *ao_loc,
         // Use opt->nbas because it is used in the prescreen function
         nbas = opt->nbas;
         opt->dm_cond = (double *)malloc(sizeof(double) * nbas*nbas);
+        if (opt->dm_cond == NULL) {
+                fprintf(stderr, "malloc(%zu) falied in CVHFsetnr_direct_scf_dm\n",
+                        sizeof(double) * nbas*nbas);
+                exit(1);
+        }
         CVHFnr_dm_cond(opt->dm_cond, dm, nset, ao_loc, atm, natm, bas, nbas, env);
 }