diff --git a/ext/openssl/ossl_cipher.c b/ext/openssl/ossl_cipher.c
index ba58594b7..f9a473caf 100644
--- a/ext/openssl/ossl_cipher.c
+++ b/ext/openssl/ossl_cipher.c
@@ -304,10 +304,12 @@ ossl_cipher_pkcs5_keyivgen(int argc, VALUE *argv, VALUE self)
         rb_raise(rb_eArgError, "iterations must be a positive integer");
     digest = NIL_P(vdigest) ? EVP_md5() : ossl_evp_md_fetch(vdigest, &md_holder);
     GetCipher(self, ctx);
-    EVP_BytesToKey(EVP_CIPHER_CTX_cipher(ctx), digest, salt,
-                   (unsigned char *)RSTRING_PTR(vpass), RSTRING_LENINT(vpass), iter, key, iv);
+    if (!EVP_BytesToKey(EVP_CIPHER_CTX_cipher(ctx), digest, salt,
+                        (unsigned char *)RSTRING_PTR(vpass),
+                        RSTRING_LENINT(vpass), iter, key, iv))
+        ossl_raise(eCipherError, "EVP_BytesToKey");
     if (EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, -1) != 1)
-        ossl_raise(eCipherError, NULL);
+        ossl_raise(eCipherError, "EVP_CipherInit_ex");
     OPENSSL_cleanse(key, sizeof key);
     OPENSSL_cleanse(iv, sizeof iv);
 
diff --git a/ext/openssl/ossl_config.c b/ext/openssl/ossl_config.c
index 71294f89a..f7a38f13b 100644
--- a/ext/openssl/ossl_config.c
+++ b/ext/openssl/ossl_config.c
@@ -451,6 +451,8 @@ Init_ossl_config(void)
      * The default system configuration file for OpenSSL.
      */
     path = CONF_get1_default_config_file();
+    if (!path)
+        rb_raise(rb_eRuntimeError, "CONF_get1_default_config_file failed");
     path_str = rb_obj_freeze(ossl_buf2str(path));
     rb_define_const(cConfig, "DEFAULT_CONFIG_FILE", path_str);
 }
diff --git a/ext/openssl/ossl_engine.c b/ext/openssl/ossl_engine.c
index 2ff44456a..cd7fb1d97 100644
--- a/ext/openssl/ossl_engine.c
+++ b/ext/openssl/ossl_engine.c
@@ -376,7 +376,8 @@ ossl_engine_set_default(VALUE self, VALUE flag)
     int f = NUM2INT(flag);
 
     GetEngine(self, e);
-    ENGINE_set_default(e, f);
+    if (!ENGINE_set_default(e, f))
+        ossl_raise(eEngineError, "ENGINE_set_default");
 
     return Qtrue;
 }
diff --git a/ext/openssl/ossl_ocsp.c b/ext/openssl/ossl_ocsp.c
index 2eaa3840f..476c35742 100644
--- a/ext/openssl/ossl_ocsp.c
+++ b/ext/openssl/ossl_ocsp.c
@@ -688,6 +688,8 @@ ossl_ocspbres_copy_nonce(VALUE self, VALUE request)
     GetOCSPBasicRes(self, bs);
     GetOCSPReq(request, req);
     ret = OCSP_copy_nonce(bs, req);
+    if (!ret)
+        ossl_raise(eOCSPError, "OCSP_copy_nonce");
 
     return INT2NUM(ret);
 }
diff --git a/ext/openssl/ossl_ssl_session.c b/ext/openssl/ossl_ssl_session.c
index 908ee453f..02ccba23b 100644
--- a/ext/openssl/ossl_ssl_session.c
+++ b/ext/openssl/ossl_ssl_session.c
@@ -185,9 +185,15 @@ static VALUE ossl_ssl_session_set_time(VALUE self, VALUE time_v)
         time_v = rb_funcall(time_v, rb_intern("to_i"), 0);
     }
 #ifdef HAVE_SSL_SESSION_GET_TIME_EX
-    SSL_SESSION_set_time_ex(ctx, NUM2TIMET(time_v));
+    time_t t = NUM2TIMET(time_v);
+    if (SSL_SESSION_set_time_ex(ctx, t) != t) {
+        ossl_raise(eSSLSession, "SSL_SESSION_set_time_ex");
+    }
 #else
-    SSL_SESSION_set_time(ctx, NUM2LONG(time_v));
+    long t = NUM2LONG(time_v);
+    if (SSL_SESSION_set_time(ctx, t) != t) {
+        ossl_raise(eSSLSession, "SSL_SESSION_set_time");
+    }
 #endif
     return ossl_ssl_session_get_time(self);
 }
@@ -205,7 +211,9 @@ static VALUE ossl_ssl_session_set_timeout(VALUE self, VALUE time_v)
 
     GetSSLSession(self, ctx);
     t = NUM2LONG(time_v);
-    SSL_SESSION_set_timeout(ctx, t);
+    if (SSL_SESSION_set_timeout(ctx, t) != 1) {
+        ossl_raise(eSSLSession, "SSL_SESSION_set_timeout");
+    }
     return ossl_ssl_session_get_timeout(self);
 }
 
@@ -249,7 +257,8 @@ static VALUE ossl_ssl_session_to_der(VALUE self)
 
     str = rb_str_new(0, len);
     p = (unsigned char *)RSTRING_PTR(str);
-    i2d_SSL_SESSION(ctx, &p);
+    if (i2d_SSL_SESSION(ctx, &p) <= 0)
+        ossl_raise(eSSLSession, "i2d_SSL_SESSION");
     ossl_str_adjust(str, p);
     return str;
 }
diff --git a/ext/openssl/ossl_ts.c b/ext/openssl/ossl_ts.c
index 697d740f0..7cef71a2c 100644
--- a/ext/openssl/ossl_ts.c
+++ b/ext/openssl/ossl_ts.c
@@ -418,7 +418,9 @@ ossl_ts_req_set_cert_requested(VALUE self, VALUE requested)
     TS_REQ *req;
 
     GetTSRequest(self, req);
-    TS_REQ_set_cert_req(req, RTEST(requested));
+    if (!TS_REQ_set_cert_req(req, RTEST(requested))) {
+        ossl_raise(eTimestampError, "TS_REQ_set_cert_req");
+    }
 
     return requested;
 }
@@ -682,6 +684,8 @@ ossl_ts_resp_get_tsa_certificate(VALUE self)
     if (!(p7 = TS_RESP_get_token(resp)))
         return Qnil;
     ts_info = sk_PKCS7_SIGNER_INFO_value(p7->d.sign->signer_info, 0);
+    if (!ts_info)
+        return Qnil;
     cert = PKCS7_cert_from_signer_info(p7, ts_info);
     if (!cert)
         return Qnil;
diff --git a/ext/openssl/ossl_x509ext.c b/ext/openssl/ossl_x509ext.c
index b559136cd..5cf8c4e97 100644
--- a/ext/openssl/ossl_x509ext.c
+++ b/ext/openssl/ossl_x509ext.c
@@ -351,7 +351,9 @@ ossl_x509ext_set_critical(VALUE self, VALUE flag)
     X509_EXTENSION *ext;
 
     GetX509Ext(self, ext);
-    X509_EXTENSION_set_critical(ext, RTEST(flag) ? 1 : 0);
+    if (!X509_EXTENSION_set_critical(ext, RTEST(flag) ? 1 : 0)) {
+        ossl_raise(eX509ExtError, "X509_EXTENSION_set_critical");
+    }
 
     return flag;
 }
@@ -382,8 +384,12 @@ ossl_x509ext_get_value(VALUE obj)
     GetX509Ext(obj, ext);
     if (!(out = BIO_new(BIO_s_mem())))
         ossl_raise(eX509ExtError, NULL);
-    if (!X509V3_EXT_print(out, ext, 0, 0))
-        ASN1_STRING_print(out, X509_EXTENSION_get_data(ext));
+    if (!X509V3_EXT_print(out, ext, 0, 0)) {
+        if (!ASN1_STRING_print(out, X509_EXTENSION_get_data(ext))) {
+            BIO_free(out);
+            ossl_raise(eX509ExtError, "ASN1_STRING_print");
+        }
+    }
     ret = ossl_membio2str(out);
 
     return ret;
diff --git a/ext/openssl/ossl_x509store.c b/ext/openssl/ossl_x509store.c
index 037a03660..0352ef1eb 100644
--- a/ext/openssl/ossl_x509store.c
+++ b/ext/openssl/ossl_x509store.c
@@ -342,7 +342,9 @@ ossl_x509store_set_purpose(VALUE self, VALUE purpose)
     int p = NUM2INT(purpose);
 
     GetX509Store(self, store);
-    X509_STORE_set_purpose(store, p);
+    if (!X509_STORE_set_purpose(store, p)) {
+        ossl_raise(eX509StoreError, "X509_STORE_set_purpose");
+    }
 
     return purpose;
 }
@@ -366,7 +368,9 @@ ossl_x509store_set_trust(VALUE self, VALUE trust)
     int t = NUM2INT(trust);
 
     GetX509Store(self, store);
-    X509_STORE_set_trust(store, t);
+    if (!X509_STORE_set_trust(store, t)) {
+        ossl_raise(eX509StoreError, "X509_STORE_set_trust");
+    }
 
     return trust;
 }
@@ -914,7 +918,9 @@ ossl_x509stctx_set_purpose(VALUE self, VALUE purpose)
     int p = NUM2INT(purpose);
 
     GetX509StCtx(self, store);
-    X509_STORE_CTX_set_purpose(store, p);
+    if (!X509_STORE_CTX_set_purpose(store, p)) {
+        ossl_raise(eX509StoreError, "X509_STORE_CTX_set_purpose");
+    }
 
     return purpose;
 }
@@ -935,7 +941,9 @@ ossl_x509stctx_set_trust(VALUE self, VALUE trust)
     int t = NUM2INT(trust);
 
     GetX509StCtx(self, store);
-    X509_STORE_CTX_set_trust(store, t);
+    if (!X509_STORE_CTX_set_trust(store, t)) {
+        ossl_raise(eX509StoreError, "X509_STORE_CTX_set_trust");
+    }
 
     return trust;
 }