diff --git a/crypto/x509/x509_test.cc b/crypto/x509/x509_test.cc
index df236aeb..551bd8ca 100644
--- a/crypto/x509/x509_test.cc
+++ b/crypto/x509/x509_test.cc
@@ -1484,19 +1484,9 @@ TEST(X509Test, NoBasicConstraintsCertSign) {
   ASSERT_TRUE(leaf);
 
   // The intermediate has keyUsage certSign, but is not marked as a CA in the
-  // basicConstraints. Sadly, since BoringSSL is based on OpenSSL 1.0.2, this is
-  // considered acceptable by default.
-  EXPECT_EQ(X509_V_OK,
+  // basicConstraints.
+  EXPECT_EQ(X509_V_ERR_INVALID_CA,
             Verify(leaf.get(), {root.get()}, {intermediate.get()}, {}, 0));
-
-  // Setting either STRICT or REQUIRE_CA_BASIC_CONSTRAINTS should trigger an
-  // error.
-  EXPECT_EQ(X509_V_ERR_INVALID_CA,
-            Verify(leaf.get(), {root.get()}, {intermediate.get()}, {},
-                   X509_V_FLAG_X509_STRICT));
-  EXPECT_EQ(X509_V_ERR_INVALID_CA,
-            Verify(leaf.get(), {root.get()}, {intermediate.get()}, {},
-                   X509_V_FLAG_REQUIRE_CA_BASIC_CONSTRAINTS));
 }
 
 TEST(X509Test, NoBasicConstraintsNetscapeCA) {
@@ -1510,17 +1500,7 @@ TEST(X509Test, NoBasicConstraintsNetscapeCA) {
   ASSERT_TRUE(leaf);
 
   // The intermediate has a Netscape certificate type of "SSL CA", but is not
-  // marked as a CA in the basicConstraints. Sadly, since BoringSSL is based on
-  // OpenSSL 1.0.2, this is considered acceptable by default.
-  EXPECT_EQ(X509_V_OK,
+  // marked as a CA in the basicConstraints.
+  EXPECT_EQ(X509_V_ERR_INVALID_CA,
             Verify(leaf.get(), {root.get()}, {intermediate.get()}, {}, 0));
-
-  // Setting either STRICT or REQUIRE_CA_BASIC_CONSTRAINTS should trigger an
-  // error.
-  EXPECT_EQ(X509_V_ERR_INVALID_CA,
-            Verify(leaf.get(), {root.get()}, {intermediate.get()}, {},
-                   X509_V_FLAG_X509_STRICT));
-  EXPECT_EQ(X509_V_ERR_INVALID_CA,
-            Verify(leaf.get(), {root.get()}, {intermediate.get()}, {},
-                   X509_V_FLAG_REQUIRE_CA_BASIC_CONSTRAINTS));
 }
diff --git a/crypto/x509/x509_vfy.c b/crypto/x509/x509_vfy.c
index fdce2510..a76eda4e 100644
--- a/crypto/x509/x509_vfy.c
+++ b/crypto/x509/x509_vfy.c
@@ -579,7 +579,7 @@ static int get_issuer_sk(X509 **issuer, X509_STORE_CTX *ctx, X509 *x)
 
 static int check_chain_extensions(X509_STORE_CTX *ctx)
 {
-    int i, ok = 0, must_be_ca, plen = 0;
+    int i, ok = 0, plen = 0;
     X509 *x;
     int (*cb) (int xok, X509_STORE_CTX *xctx);
     int proxy_path_length = 0;
@@ -587,15 +587,13 @@ static int check_chain_extensions(X509_STORE_CTX *ctx)
     int allow_proxy_certs;
     cb = ctx->verify_cb;
 
-    /*
-     * must_be_ca can have 1 of 3 values: -1: we accept both CA and non-CA
-     * certificates, to allow direct use of self-signed certificates (which
-     * are marked as CA). 0: we only accept non-CA certificates.  This is
-     * currently not used, but the possibility is present for future
-     * extensions. 1: we only accept CA certificates.  This is currently used
-     * for all certificates in the chain except the leaf certificate.
-     */
-    must_be_ca = -1;
+    enum {
+        // ca_or_leaf allows either type of certificate so that direct use of
+        // self-signed certificates works.
+        ca_or_leaf,
+        must_be_ca,
+        must_not_be_ca,
+    } ca_requirement;
 
     /* CRL path validation */
     if (ctx->parent) {
@@ -607,6 +605,8 @@ static int check_chain_extensions(X509_STORE_CTX *ctx)
         purpose = ctx->param->purpose;
     }
 
+    ca_requirement = ca_or_leaf;
+
     /* Check all untrusted certificates */
     for (i = 0; i < ctx->last_untrusted; i++) {
         int ret;
@@ -628,37 +628,30 @@ static int check_chain_extensions(X509_STORE_CTX *ctx)
             if (!ok)
                 goto end;
         }
-        ret = X509_check_ca(x);
-        switch (must_be_ca) {
-        case -1:
-            if ((ctx->param->flags & X509_V_FLAG_X509_STRICT)
-                && (ret != 1) && (ret != 0)) {
-                ret = 0;
-                ctx->error = X509_V_ERR_INVALID_CA;
-            } else
-                ret = 1;
+
+        switch (ca_requirement) {
+        case ca_or_leaf:
+            ret = 1;
             break;
-        case 0:
-            if (ret != 0) {
+        case must_not_be_ca:
+            if (X509_check_ca(x)) {
                 ret = 0;
                 ctx->error = X509_V_ERR_INVALID_NON_CA;
             } else
                 ret = 1;
             break;
-        default:
-            if ((ret == 0)
-                || ((ctx->param->flags & X509_V_FLAG_X509_STRICT)
-                    && (ret != 1))
-                || ((ctx->param->flags &
-                     X509_V_FLAG_REQUIRE_CA_BASIC_CONSTRAINTS)
-                    && (ret != 1))
-                ) {
+        case must_be_ca:
+            if (!X509_check_ca(x)) {
                 ret = 0;
                 ctx->error = X509_V_ERR_INVALID_CA;
             } else
                 ret = 1;
             break;
+        default:
+            // impossible.
+            ret = 0;
         }
+
         if (ret == 0) {
             ctx->error_depth = i;
             ctx->current_cert = x;
@@ -667,7 +660,7 @@ static int check_chain_extensions(X509_STORE_CTX *ctx)
                 goto end;
         }
         if (ctx->param->purpose > 0) {
-            ret = X509_check_purpose(x, purpose, must_be_ca > 0);
+            ret = X509_check_purpose(x, purpose, ca_requirement == must_be_ca);
             if ((ret == 0)
                 || ((ctx->param->flags & X509_V_FLAG_X509_STRICT)
                     && (ret != 1))) {
@@ -708,9 +701,10 @@ static int check_chain_extensions(X509_STORE_CTX *ctx)
                     goto end;
             }
             proxy_path_length++;
-            must_be_ca = 0;
-        } else
-            must_be_ca = 1;
+            ca_requirement = must_not_be_ca;
+        } else {
+            ca_requirement = must_be_ca;
+        }
     }
     ok = 1;
  end:
diff --git a/crypto/x509v3/v3_purp.c b/crypto/x509v3/v3_purp.c
index f70a804c..0275b1bb 100644
--- a/crypto/x509v3/v3_purp.c
+++ b/crypto/x509v3/v3_purp.c
@@ -80,7 +80,6 @@
 
 static void x509v3_cache_extensions(X509 *x);
 
-static int check_ssl_ca(const X509 *x);
 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
                                     int ca);
 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
@@ -563,39 +562,20 @@ static void x509v3_cache_extensions(X509 *x)
     CRYPTO_MUTEX_unlock_write(&x->lock);
 }
 
-/*
- * CA checks common to all purposes return codes: 0 not a CA 1 is a CA 2
- * basicConstraints absent so "maybe" a CA 3 basicConstraints absent but self
- * signed V1. 4 basicConstraints absent but keyUsage present and keyCertSign
- * asserted.
- */
-
+/* check_ca returns one if |x| should be considered a CA certificate and zero
+ * otherwise. */
 static int check_ca(const X509 *x)
 {
     /* keyUsage if present should allow cert signing */
     if (ku_reject(x, KU_KEY_CERT_SIGN))
         return 0;
-    if (x->ex_flags & EXFLAG_BCONS) {
-        if (x->ex_flags & EXFLAG_CA)
-            return 1;
-        /* If basicConstraints says not a CA then say so */
-        else
-            return 0;
-    } else {
-        /* we support V1 roots for...  uh, I don't really know why. */
-        if ((x->ex_flags & V1_ROOT) == V1_ROOT)
-            return 3;
-        /*
-         * If key usage present it must have certSign so tolerate it
-         */
-        else if (x->ex_flags & EXFLAG_KUSAGE)
-            return 4;
-        /* Older certificates could have Netscape-specific CA types */
-        else if (x->ex_flags & EXFLAG_NSCERT && x->ex_nscert & NS_ANY_CA)
-            return 5;
-        /* can this still be regarded a CA certificate?  I doubt it */
-        return 0;
+    /* Version 1 certificates are considered CAs and don't have extensions. */
+    if ((x->ex_flags & V1_ROOT) == V1_ROOT) {
+        return 1;
     }
+    /* Otherwise, it's only a CA if basicConstraints says so. */
+    return ((x->ex_flags & EXFLAG_BCONS) &&
+            (x->ex_flags & EXFLAG_CA));
 }
 
 int X509_check_ca(X509 *x)
@@ -604,27 +584,13 @@ int X509_check_ca(X509 *x)
     return check_ca(x);
 }
 
-/* Check SSL CA: common checks for SSL client and server */
-static int check_ssl_ca(const X509 *x)
-{
-    int ca_ret;
-    ca_ret = check_ca(x);
-    if (!ca_ret)
-        return 0;
-    /* check nsCertType if present */
-    if (ca_ret != 5 || x->ex_nscert & NS_SSL_CA)
-        return ca_ret;
-    else
-        return 0;
-}
-
 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x,
                                     int ca)
 {
     if (xku_reject(x, XKU_SSL_CLIENT))
         return 0;
     if (ca)
-        return check_ssl_ca(x);
+        return check_ca(x);
     /* We need to do digital signatures or key agreement */
     if (ku_reject(x, KU_DIGITAL_SIGNATURE | KU_KEY_AGREEMENT))
         return 0;
@@ -648,7 +614,7 @@ static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x,
     if (xku_reject(x, XKU_SSL_SERVER | XKU_SGC))
         return 0;
     if (ca)
-        return check_ssl_ca(x);
+        return check_ca(x);
 
     if (ns_reject(x, NS_SSL_SERVER))
         return 0;
@@ -678,15 +644,13 @@ static int purpose_smime(const X509 *x, int ca)
     if (xku_reject(x, XKU_SMIME))
         return 0;
     if (ca) {
-        int ca_ret;
-        ca_ret = check_ca(x);
-        if (!ca_ret)
-            return 0;
         /* check nsCertType if present */
-        if (ca_ret != 5 || x->ex_nscert & NS_SMIME_CA)
-            return ca_ret;
-        else
-            return 0;
+        if ((x->ex_flags & EXFLAG_NSCERT) &&
+            (x->ex_nscert & NS_SMIME_CA) == 0) {
+          return 0;
+        }
+
+        return check_ca(x);
     }
     if (x->ex_flags & EXFLAG_NSCERT) {
         if (x->ex_nscert & NS_SMIME)
@@ -727,11 +691,7 @@ static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
                                   int ca)
 {
     if (ca) {
-        int ca_ret;
-        if ((ca_ret = check_ca(x)) != 2)
-            return ca_ret;
-        else
-            return 0;
+        return check_ca(x);
     }
     if (ku_reject(x, KU_CRL_SIGN))
         return 0;
@@ -745,10 +705,6 @@ static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x,
 
 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
 {
-    /*
-     * Must be a valid CA.  Should we really support the "I don't know" value
-     * (2)?
-     */
     if (ca)
         return check_ca(x);
     /* leaf certificate is checked in OCSP_verify() */
diff --git a/include/openssl/x509_vfy.h b/include/openssl/x509_vfy.h
index 6a7c554c..1d4ea5a7 100644
--- a/include/openssl/x509_vfy.h
+++ b/include/openssl/x509_vfy.h
@@ -382,7 +382,8 @@ OPENSSL_EXPORT void X509_STORE_CTX_set_depth(X509_STORE_CTX *ctx, int depth);
 #define	X509_V_FLAG_CRL_CHECK_ALL		0x8
 /* Ignore unhandled critical extensions */
 #define	X509_V_FLAG_IGNORE_CRITICAL		0x10
-/* Disable workarounds for broken certificates */
+/* Enforces stricter checking on certificate purposes.
+ * TODO(agl): eliminate. */
 #define	X509_V_FLAG_X509_STRICT			0x20
 /* Enable proxy certificate validation */
 #define	X509_V_FLAG_ALLOW_PROXY_CERTS		0x40
@@ -410,8 +411,6 @@ OPENSSL_EXPORT void X509_STORE_CTX_set_depth(X509_STORE_CTX *ctx, int depth);
 #define X509_V_FLAG_SUITEB_192_LOS		0x20000
 /* Suite B 128 bit mode allowing 192 bit algorithms */
 #define X509_V_FLAG_SUITEB_128_LOS		0x30000
-/* Disable workarounds for broken certificates */
-#define X509_V_FLAG_REQUIRE_CA_BASIC_CONSTRAINTS	0x40000
 
 /* Allow partial chains if at least one certificate is in trusted store */
 #define X509_V_FLAG_PARTIAL_CHAIN		0x80000