diff --git a/src/client/linux/microdump_writer/microdump_writer.cc b/src/client/linux/microdump_writer/microdump_writer.cc
index 247387e2..d54d4909 100644
--- a/src/client/linux/microdump_writer/microdump_writer.cc
+++ b/src/client/linux/microdump_writer/microdump_writer.cc
@@ -166,8 +166,9 @@ class MicrodumpWriter {
     const char kOSId[] = "L";
 #endif
 
-// We cannot depend on uts.machine. On multiarch devices it always returns the
-// primary arch, not the one that match the executable being run.
+// Dump the runtime architecture. On multiarch devices it might not match the
+// hw architecture (the one returned by uname()), for instance in the case of
+// a 32-bit app running on a aarch64 device.
 #if defined(__aarch64__)
     const char kArch[] = "arm64";
 #elif defined(__ARMEL__)
@@ -189,21 +190,24 @@ class MicrodumpWriter {
     LogAppend(" ");
     LogAppend(n_cpus);
     LogAppend(" ");
+
+    // Dump the HW architecture (e.g., armv7l, aarch64).
+    struct utsname uts;
+    const bool has_uts_info = (uname(&uts) == 0);
+    const char* hwArch = has_uts_info ? uts.machine : "unknown_hw_arch";
+    LogAppend(hwArch);
+    LogAppend(" ");
+
     // If the client has attached a build fingerprint to the MinidumpDescriptor
     // use that one. Otherwise try to get some basic info from uname().
     if (build_fingerprint_) {
       LogAppend(build_fingerprint_);
+    } else if (has_uts_info) {
+      LogAppend(uts.release);
+      LogAppend(" ");
+      LogAppend(uts.version);
     } else {
-      struct utsname uts;
-      if (uname(&uts) == 0) {
-        LogAppend(uts.machine);
-        LogAppend(" ");
-        LogAppend(uts.release);
-        LogAppend(" ");
-        LogAppend(uts.version);
-      } else {
-        LogAppend("no build fingerprint available");
-      }
+      LogAppend("no build fingerprint available");
     }
     LogCommitLine();
   }
diff --git a/src/client/linux/microdump_writer/microdump_writer_unittest.cc b/src/client/linux/microdump_writer/microdump_writer_unittest.cc
index 1fa6f1ff..035e73c1 100644
--- a/src/client/linux/microdump_writer/microdump_writer_unittest.cc
+++ b/src/client/linux/microdump_writer/microdump_writer_unittest.cc
@@ -27,10 +27,12 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+#include <ctype.h>
 #include <sys/syscall.h>
 #include <sys/types.h>
 #include <unistd.h>
 
+#include <sstream>
 #include <string>
 
 #include "breakpad_googletest_includes.h"
@@ -103,7 +105,40 @@ void CrashAndGetMicrodump(
       buf->get(), "-----BEGIN BREAKPAD MICRODUMP-----"));
   ASSERT_NE(static_cast<char*>(0), strstr(
       buf->get(), "-----END BREAKPAD MICRODUMP-----"));
+}
 
+void CheckMicrodumpContents(const string &microdum_content,
+                            const string &expected_fingerprint,
+                            const string &expected_product_info) {
+  std::istringstream iss(microdum_content);
+  bool did_find_os_info = false;
+  bool did_find_product_info = false;
+  for (string line; std::getline(iss, line);) {
+    if (line.find("O ") == 0) {
+      std::istringstream os_info_tokens(line);
+      string token;
+      os_info_tokens.ignore(2); // Ignore the "O " preamble.
+      // Check the OS descriptor char (L=Linux, A=Android).
+      os_info_tokens >> token;
+      ASSERT_TRUE(token == "L" || token == "A");
+
+      os_info_tokens >> token; // HW architecture.
+      os_info_tokens >> token; // Number of cpus.
+      for (size_t i = 0; i < token.size(); ++i)
+        ASSERT_TRUE(isxdigit(token[i]));
+      os_info_tokens >> token; // SW architecture.
+
+      // Check that the build fingerprint is in the right place.
+      os_info_tokens >> token;
+      ASSERT_EQ(expected_fingerprint, token);
+      did_find_os_info = true;
+    } else if (line.find("V ") == 0) {
+      ASSERT_EQ("V " + expected_product_info, line);
+      did_find_product_info = true;
+    }
+  }
+  ASSERT_TRUE(did_find_os_info);
+  ASSERT_TRUE(did_find_product_info);
 }
 
 TEST(MicrodumpWriterTest, BasicWithMappings) {
@@ -156,9 +191,15 @@ TEST(MicrodumpWriterTest, BuildFingerprintAndProductInfo) {
   MappingList no_mappings;
 
   CrashAndGetMicrodump(no_mappings, kBuildFingerprint, kProductInfo, &buf);
-
-  ASSERT_NE(static_cast<char*>(0), strstr(buf.get(), kBuildFingerprint));
-  ASSERT_NE(static_cast<char*>(0), strstr(buf.get(), kProductInfo));
+  CheckMicrodumpContents(string(buf.get()), kBuildFingerprint, kProductInfo);
 }
 
+TEST(MicrodumpWriterTest, NoProductInfo) {
+  const char kBuildFingerprint[] = "foobar";
+  scoped_array<char> buf;
+  MappingList no_mappings;
+
+  CrashAndGetMicrodump(no_mappings, kBuildFingerprint, NULL, &buf);
+  CheckMicrodumpContents(string(buf.get()), kBuildFingerprint, "UNKNOWN:0.0.0.0");
+}
 }  // namespace