diff --git a/build/parsePreamble.c b/build/parsePreamble.c
index de205d5f8e..8d1d85464b 100644
--- a/build/parsePreamble.c
+++ b/build/parsePreamble.c
@@ -48,6 +48,15 @@ static const rpmTagVal copyTagsDuringParse[] = {
     0
 };
 
+/**
+ */
+static const rpmTagVal requiredTagsForBuild[] = {
+    RPMTAG_NAME,
+    RPMTAG_VERSION,
+    RPMTAG_RELEASE,
+    0
+};
+
 /**
  */
 static const rpmTagVal requiredTags[] = {
@@ -415,7 +424,7 @@ static inline char * findLastChar(char * s)
 
 /**
  */
-static int isMemberInEntry(Header h, const char *name, rpmTagVal tag)
+int isMemberInEntry(Header h, const char *name, rpmTagVal tag)
 {
     struct rpmtd_s td;
     int found = 0;
@@ -437,7 +446,7 @@ static int isMemberInEntry(Header h, const char *name, rpmTagVal tag)
 
 /**
  */
-static rpmRC checkForValidArchitectures(rpmSpec spec)
+rpmRC checkForValidArchitectures(rpmSpec spec)
 {
     char *arch = rpmExpand("%{_target_cpu}", NULL);
     char *os = rpmExpand("%{_target_os}", NULL);
@@ -483,7 +492,7 @@ static rpmRC checkForValidArchitectures(rpmSpec spec)
  * @param NVR		package name-version-release
  * @return		RPMRC_OK if OK
  */
-static int checkForRequired(Header h, const char * NVR)
+int checkForRequired(Header h)
 {
     int res = RPMRC_OK;
     const rpmTagVal * p;
@@ -492,7 +501,30 @@ static int checkForRequired(Header h, const char * NVR)
 	if (!headerIsEntry(h, *p)) {
 	    rpmlog(RPMLOG_ERR,
 			_("%s field must be present in package: %s\n"),
-			rpmTagGetName(*p), NVR);
+			rpmTagGetName(*p), headerGetString(h, RPMTAG_NAME));
+	    res = RPMRC_FAIL;
+	}
+    }
+
+    return res;
+}
+
+/**
+ * Check that required tags are present in header.
+ * @param h		header
+ * @param NVR		package name-version-release
+ * @return		RPMRC_OK if OK
+ */
+static int checkForRequiredForBuild(Header h)
+{
+    int res = RPMRC_OK;
+    const rpmTagVal * p;
+
+    for (p = requiredTagsForBuild; *p != 0; p++) {
+	if (!headerIsEntry(h, *p)) {
+	    rpmlog(RPMLOG_ERR,
+			_("%s field must be present before build in package: %s\n"),
+			rpmTagGetName(*p), headerGetString(h, RPMTAG_NAME));
 	    res = RPMRC_FAIL;
 	}
     }
@@ -506,7 +538,7 @@ static int checkForRequired(Header h, const char * NVR)
  * @param NVR		package name-version-release
  * @return		RPMRC_OK if OK
  */
-static int checkForDuplicates(Header h, const char * NVR)
+int checkForDuplicates(Header h)
 {
     int res = RPMRC_OK;
     rpmTagVal tag, lastTag = RPMTAG_NOT_FOUND;
@@ -515,7 +547,7 @@ static int checkForDuplicates(Header h, const char * NVR)
     while ((tag = headerNextTag(hi)) != RPMTAG_NOT_FOUND) {
 	if (tag == lastTag) {
 	    rpmlog(RPMLOG_ERR, _("Duplicate %s entries in package: %s\n"),
-		     rpmTagGetName(tag), NVR);
+		     rpmTagGetName(tag), headerGetString(h, RPMTAG_NAME));
 	    res = RPMRC_FAIL;
 	}
 	lastTag = tag;
@@ -545,7 +577,7 @@ static struct optionalTag {
 
 /**
  */
-static void fillOutMainPackage(Header h)
+void fillOutMainPackage(Header h)
 {
     const struct optionalTag *ot;
 
@@ -1153,11 +1185,13 @@ int parsePreamble(rpmSpec spec, int initialPackage)
 	    NVR = xstrdup(name);
 	pkg = newPackage(NVR, spec->pool, &spec->packages);
 	headerPutString(pkg->header, RPMTAG_NAME, NVR);
+    } else if (spec->sourcePackage) {
+	NVR = xstrdup("(main package)");
+	pkg = spec->packages;
     } else {
 	NVR = xstrdup("(main package)");
 	pkg = newPackage(NULL, spec->pool, &spec->packages);
 	spec->sourcePackage = newPackage(NULL, spec->pool, NULL);
-	
     }
 
     if ((rc = readLine(spec, STRIP_TRAILINGSPACE | STRIP_COMMENTS)) > 0) {
@@ -1212,6 +1246,10 @@ int parsePreamble(rpmSpec spec, int initialPackage)
      * can't be messed with by anything spec does beyond this point.
      */
     if (initialPackage) {
+	if (checkForRequiredForBuild(pkg->header)) {
+	    goto exit;
+	}
+
 	char *buildRoot = rpmGetPath(spec->buildRoot, NULL);
 	free(spec->buildRoot);
 	spec->buildRoot = buildRoot;
@@ -1226,32 +1264,6 @@ int parsePreamble(rpmSpec spec, int initialPackage)
 	}
     }
 
-    /* XXX Skip valid arch check if not building binary package */
-    if (!(spec->flags & RPMSPEC_ANYARCH) && checkForValidArchitectures(spec)) {
-	goto exit;
-    }
-
-    /* It is the main package */
-    if (pkg == spec->packages) {
-	fillOutMainPackage(pkg->header);
-	/* Define group tag to something when group is undefined in main package*/
-	if (!headerIsEntry(pkg->header, RPMTAG_GROUP)) {
-	    headerPutString(pkg->header, RPMTAG_GROUP, "Unspecified");
-	}
-    }
-
-    if (checkForDuplicates(pkg->header, NVR)) {
-	goto exit;
-    }
-
-    if (pkg != spec->packages) {
-	copyInheritedTags(pkg->header, spec->packages->header);
-    }
-
-    if (checkForRequired(pkg->header, NVR)) {
-	goto exit;
-    }
-
     /* if we get down here nextPart has been set to non-error */
     res = nextPart;
 
diff --git a/build/parseSpec.c b/build/parseSpec.c
index 3929c0a26c..9a24d13114 100644
--- a/build/parseSpec.c
+++ b/build/parseSpec.c
@@ -652,6 +652,10 @@ static void initSourceHeader(rpmSpec spec)
     if (headerIsEntry(sourcePkg->header, RPMTAG_NAME))
 	return;
 
+    char *os = rpmExpand("%{_target_os}", NULL);
+    headerPutString(sourcePkg->header, RPMTAG_OS, os);
+    free(os);
+
     /* Only specific tags are added to the source package header */
     headerCopyTags(spec->packages->header, sourcePkg->header, sourceTags);
 
@@ -694,11 +698,17 @@ static void initSourceHeader(rpmSpec spec)
 	    }
 	}
     }
+}
+
+static void finalizeSourceHeader(rpmSpec spec)
+{
+    /* Only specific tags are added to the source package header */
+    headerCopyTags(spec->packages->header, spec->sourcePackage->header, sourceTags);
 
     /* Provide all package NEVRs that would be built */
     for (Package p = spec->packages; p != NULL; p = p->next) {
 	if (p->fileList) {
-	    Header h = sourcePkg->header;
+	    Header h = spec->sourcePackage->header;
 	    uint32_t dsflags = rpmdsFlags(p->ds);
 	    headerPutString(h, RPMTAG_PROVIDENAME, rpmdsN(p->ds));
 	    headerPutUint32(h, RPMTAG_PROVIDEFLAGS, &dsflags, 1);
@@ -733,37 +743,17 @@ void addPackageProvides(Package pkg)
     free(evr);
 }
 
-static void addTargets(Package Pkgs)
+static void addArch(rpmSpec spec)
 {
-    char *platform = rpmExpand("%{_target_platform}", NULL);
     char *arch = rpmExpand("%{_target_cpu}", NULL);
-    char *os = rpmExpand("%{_target_os}", NULL);
-    char *optflags = rpmExpand("%{optflags}", NULL);
 
-    for (Package pkg = Pkgs; pkg != NULL; pkg = pkg->next) {
-	if (headerIsEntry(pkg->header, RPMTAG_OS)) {
-	    continue;
-	}
-	headerPutString(pkg->header, RPMTAG_OS, os);
+    for (Package pkg = spec->packages; pkg != NULL; pkg = pkg->next) {
 	/* noarch subpackages already have arch set here, leave it alone */
 	if (!headerIsEntry(pkg->header, RPMTAG_ARCH)) {
 	    headerPutString(pkg->header, RPMTAG_ARCH, arch);
 	}
-	headerPutString(pkg->header, RPMTAG_PLATFORM, platform);
-	headerPutString(pkg->header, RPMTAG_OPTFLAGS, optflags);
-
-	/* Add manual dependencies early for rpmspec etc to look at */
-	addPackageProvides(pkg);
-	for (int i=0; i<PACKAGE_NUM_DEPS; i++) {
-	    rpmdsPutToHeader(pkg->dependencies[i], pkg->header);
-	}
-
-	pkg->ds = rpmdsThis(pkg->header, RPMTAG_REQUIRENAME, RPMSENSE_EQUAL);
     }
-    free(platform);
     free(arch);
-    free(os);
-    free(optflags);
 }
 
 rpmRC checkForEncoding(Header h, int addtag)
@@ -901,12 +891,6 @@ static rpmRC parseSpecSection(rpmSpec *specptr, int secondary)
     int storedParsePart;
     int initialPackage = 1;
 
-    if (secondary) {
-	initialPackage = 0;
-	parsePart = PART_EMPTY;
-	prevParsePart = PART_NONE;
-    }
-
     /* All the parse*() functions expect to have a line pre-read */
     /* in the spec's line buffer.  Except for parsePreamble(),   */
     /* which handles the initial entry into a spec file.         */
@@ -1053,17 +1037,8 @@ static rpmRC parseSpecSection(rpmSpec *specptr, int secondary)
 	}
     }
 
-    /* Check for description in each package */
-    for (Package pkg = spec->packages; pkg != NULL; pkg = pkg->next) {
-	if (!headerIsEntry(pkg->header, RPMTAG_DESCRIPTION)) {
-	    rpmlog(RPMLOG_ERR, _("Package has no %%description: %s\n"),
-		   headerGetString(pkg->header, RPMTAG_NAME));
-	    goto errxit;
-	}
-    }
-
-    /* Add arch, os and platform, self-provides etc for each package */
-    addTargets(spec->packages);
+    /* Add arch for each package */
+    addArch(spec);
 
     /* Check for encoding in each package unless disabled */
     if (!(spec->flags & RPMSPEC_NOUTF8)) {
@@ -1128,10 +1103,74 @@ static rpmSpec parseSpec(const char *specFile, rpmSpecFlags flags,
     return NULL;
 }
 
+static rpmRC finalizeSpec(rpmSpec spec)
+{
+    rpmRC rc = RPMRC_FAIL;
+
+    char *platform = rpmExpand("%{_target_platform}", NULL);
+    char *os = rpmExpand("%{_target_os}", NULL);
+    char *optflags = rpmExpand("%{optflags}", NULL);
+
+    /* XXX Skip valid arch check if not building binary package */
+    if (!(spec->flags & RPMSPEC_ANYARCH) && checkForValidArchitectures(spec)) {
+	goto exit;
+    }
+
+    fillOutMainPackage(spec->packages->header);
+    /* Define group tag to something when group is undefined in main package*/
+    if (!headerIsEntry(spec->packages->header, RPMTAG_GROUP)) {
+	headerPutString(spec->packages->header, RPMTAG_GROUP, "Unspecified");
+    }
+
+    for (Package pkg = spec->packages; pkg != NULL; pkg = pkg->next) {
+	headerPutString(pkg->header, RPMTAG_OS, os);
+	headerPutString(pkg->header, RPMTAG_PLATFORM, platform);
+	headerPutString(pkg->header, RPMTAG_OPTFLAGS, optflags);
+
+	if (pkg != spec->packages) {
+	    copyInheritedTags(pkg->header, spec->packages->header);
+	}
+
+	/* Add manual dependencies early for rpmspec etc to look at */
+	addPackageProvides(pkg);
+
+	for (int i=0; i<PACKAGE_NUM_DEPS; i++) {
+	    rpmdsPutToHeader(pkg->dependencies[i], pkg->header);
+	}
+
+	pkg->ds = rpmdsThis(pkg->header, RPMTAG_REQUIRENAME, RPMSENSE_EQUAL);
+
+	if (checkForRequired(pkg->header)) {
+	    goto exit;
+	}
+	if (!headerIsEntry(pkg->header, RPMTAG_DESCRIPTION)) {
+	    rpmlog(RPMLOG_ERR, _("Package has no %%description: %s\n"),
+		   headerGetString(pkg->header, RPMTAG_NAME));
+	    goto exit;
+	}
+	if (checkForDuplicates(pkg->header)) {
+	    goto exit;
+	}
+    }
+
+    finalizeSourceHeader(spec);
+
+    rc = RPMRC_OK;
+ exit:
+    free(platform);
+    free(os);
+    free(optflags);
+    return rc;
+}
+
 rpmSpec rpmSpecParse(const char *specFile, rpmSpecFlags flags,
 		     const char *buildRoot)
 {
-    return parseSpec(specFile, flags, buildRoot, 0);
+    rpmSpec spec = parseSpec(specFile, flags, buildRoot, 0);
+    if (spec && !(flags & RPMSPEC_NOFINALIZE)) {
+	finalizeSpec(spec);
+    }
+    return spec;
 }
 
 rpmRC parseGeneratedSpecs(rpmSpec spec)
@@ -1158,5 +1197,11 @@ rpmRC parseGeneratedSpecs(rpmSpec spec)
 	argvFree(argv);
     }
     free(specPattern);
+    if (!rc) {
+	rc = finalizeSpec(spec);
+	if (rc != RPMRC_OK) {
+	    rpmlog(RPMLOG_ERR, "parsing failed\n");
+	}
+    }
     return rc;
 }
diff --git a/build/rpmbuild_internal.h b/build/rpmbuild_internal.h
index 9021def2c1..ddf1ea7bdf 100644
--- a/build/rpmbuild_internal.h
+++ b/build/rpmbuild_internal.h
@@ -621,6 +621,25 @@ void * specLuaFini(rpmSpec spec);
 
 RPM_GNUC_INTERNAL
 void addLuaSource(const struct Source *p);
+
+RPM_GNUC_INTERNAL
+int isMemberInEntry(Header h, const char *name, rpmTagVal tag);
+
+RPM_GNUC_INTERNAL
+rpmRC checkForValidArchitectures(rpmSpec spec);
+
+RPM_GNUC_INTERNAL
+int checkForRequired(Header h);
+
+RPM_GNUC_INTERNAL
+int checkForDuplicates(Header h);
+
+RPM_GNUC_INTERNAL
+void fillOutMainPackage(Header h);
+
+RPM_GNUC_INTERNAL
+void copyInheritedTags(Header h, Header fromh);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/include/rpm/rpmspec.h b/include/rpm/rpmspec.h
index 1ec3383123..a3239b844a 100644
--- a/include/rpm/rpmspec.h
+++ b/include/rpm/rpmspec.h
@@ -37,6 +37,7 @@ enum rpmSpecFlags_e {
     RPMSPEC_FORCE	= (1 << 1),
     RPMSPEC_NOLANG	= (1 << 2),
     RPMSPEC_NOUTF8	= (1 << 3),
+    RPMSPEC_NOFINALIZE  = (1 << 4),
 };
 
 typedef rpmFlags rpmSpecFlags;
diff --git a/tests/data/SPECS/dynamic.spec b/tests/data/SPECS/dynamic.spec
index 5dbaa8584e..ce31ed2828 100644
--- a/tests/data/SPECS/dynamic.spec
+++ b/tests/data/SPECS/dynamic.spec
@@ -1,12 +1,14 @@
-Summary: dynamic hello -- hello, world rpm
 Name: dynamic
 Version: 1.0
 Release: 1
+BuildArch: noarch
+%{?!FULLDYNAMIC:
 Group: Utilities
 License: GPL
 Distribution: RPM test suite.
 URL: http://rpm.org
-BuildArch:	noarch
+Summary: dynamic hello -- hello, world rpm
+}
 
 %description
 Simple rpm demonstration.
@@ -21,6 +23,20 @@ echo "Q: Why?\nA: Because we can!" > FAQ
 mkdir -p $RPM_BUILD_ROOT/usr/local/bin
 echo " " > $RPM_BUILD_ROOT/usr/local/bin/hello
 
+%{?FULLDYNAMIC:
+echo "Group: Utilities" >> %{specpartsdir}/mainpkg.specpart
+echo "License: GPL" >> %{specpartsdir}/mainpkg.specpart
+echo "Distribution: RPM test suite." >> %{specpartsdir}/mainpkg.specpart
+echo "URL: http://rpm.org" >> %{specpartsdir}/mainpkg.specpart
+echo "Summary: dynamic hello -- hello, world rpm" >> %{specpartsdir}/mainpkg.specpart
+%{?DOUBLESUMMARY:
+echo "Summary: dynamic hello -- hello, world again" >> %{specpartsdir}/mainpkg.specpart
+}
+%{?WRONGTAG:
+echo "LicenseToKill: True" >> %{specpartsdir}/mainpkg.specpart
+}
+
+}
 
 echo "%package docs" >> %{specpartsdir}/docs.specpart
 %{?!FAIL:echo "Summary: Documentation for dynamic spec" >> %{specpartsdir}/docs.specpart}
diff --git a/tests/rpmbuild.at b/tests/rpmbuild.at
index 0d28354084..2851f2f66d 100644
--- a/tests/rpmbuild.at
+++ b/tests/rpmbuild.at
@@ -2406,6 +2406,32 @@ runroot rpm -ql /build/RPMS/noarch/dynamic-docs-1.0-1.noarch.rpm
 [])
 RPMTEST_CLEANUP
 
+# ------------------------------
+# Check if dynamic spec generation works for main package, too
+AT_SETUP([rpmbuild with dynamic spec generation for main package])
+AT_KEYWORDS([build])
+RPMDB_INIT
+RPMTEST_CHECK([
+
+runroot rpmbuild --define "_prefix /usr/local" -D "FULLDYNAMIC 1" -ba /data/SPECS/dynamic.spec
+],
+[0],
+[ignore],
+[ignore])
+
+RPMTEST_CHECK([
+
+runroot rpm -qp --qf "%{Summary}\n" /build/RPMS/noarch/dynamic-docs-1.0-1.noarch.rpm
+runroot rpm -ql /build/RPMS/noarch/dynamic-docs-1.0-1.noarch.rpm
+],
+[0],
+[Documentation for dynamic spec
+/usr/local/share/doc/dynamic-docs-1.0
+/usr/local/share/doc/dynamic-docs-1.0/FAQ
+],
+[])
+RPMTEST_CLEANUP
+
 # ------------------------------
 # Check failing dynamic spec generation
 AT_SETUP([rpmbuild with dynamic spec generation fail])
@@ -2423,6 +2449,40 @@ error: parsing failed
 
 RPMTEST_CLEANUP
 
+# ------------------------------
+# Check failing dynamic spec generation
+AT_SETUP([rpmbuild with dynamic spec generation fail])
+AT_KEYWORDS([build])
+RPMDB_INIT
+RPMTEST_CHECK([
+
+runroot rpmbuild --quiet -D "FULLDYNAMIC 1" -D "DOUBLESUMMARY 1" -ba /data/SPECS/dynamic.spec
+],
+[0],
+[],
+[warning: line 6: second Summary
+])
+
+RPMTEST_CLEANUP
+
+# ------------------------------
+# Check failing dynamic spec generation
+AT_SETUP([rpmbuild with dynamic spec generation fail])
+AT_KEYWORDS([build])
+RPMDB_INIT
+RPMTEST_CHECK([
+
+runroot rpmbuild --quiet -D "FULLDYNAMIC 1" -D "WRONGTAG 1" -ba /data/SPECS/dynamic.spec
+],
+[1],
+[],
+[error: line 6: Unknown tag: LicenseToKill: True
+error: parsing failed
+])
+
+RPMTEST_CLEANUP
+
+
 # ------------------------------
 # Check source name with space
 AT_SETUP([rpmbuild source name with space])
diff --git a/tools/rpmbuild.c b/tools/rpmbuild.c
index 16fba7767a..724dee82ac 100644
--- a/tools/rpmbuild.c
+++ b/tools/rpmbuild.c
@@ -63,7 +63,7 @@ static struct rpmBuildArguments_s rpmBTArgs;
 
 extern int _fsm_debug;
 
-static rpmSpecFlags spec_flags = 0;	/*!< Bit(s) to control spec parsing. */
+static rpmSpecFlags spec_flags = RPMSPEC_NOFINALIZE; /*!< Bit(s) to control spec parsing. */
 static int noDeps = 0;			/*!< from --nodeps */
 static int shortCircuit = 0;		/*!< from --short-circuit */
 static char buildMode = 0;		/*!< Build mode (one of "btBC") */