diff --git a/gnu/local.mk b/gnu/local.mk
index 3c11e3adde..3b2bde7290 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -781,6 +781,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/ninja-tests.patch			\
   %D%/packages/patches/ninja-zero-mtime.patch			\
   %D%/packages/patches/node-9077.patch				\
+  %D%/packages/patches/nss-increase-test-timeout.patch		\
   %D%/packages/patches/nss-pkgconfig.patch			\
   %D%/packages/patches/ntfs-3g-CVE-2017-0358.patch		\
   %D%/packages/patches/nvi-assume-preserve-path.patch		\
diff --git a/gnu/packages/gnuzilla.scm b/gnu/packages/gnuzilla.scm
index afb5ad3061..4759b9236f 100644
--- a/gnu/packages/gnuzilla.scm
+++ b/gnu/packages/gnuzilla.scm
@@ -200,7 +200,8 @@ (define-public nss
                (base32
                 "149807rmzb76hnh48rw4m9jw83iw0168njzchz0hmbsgc8mk0i5w"))
               ;; Create nss.pc and nss-config.
-              (patches (search-patches "nss-pkgconfig.patch"))))
+              (patches (search-patches "nss-pkgconfig.patch"
+                                       "nss-increase-test-timeout.patch"))))
     (build-system gnu-build-system)
     (outputs '("out" "bin"))
     (arguments
diff --git a/gnu/packages/patches/nss-increase-test-timeout.patch b/gnu/packages/patches/nss-increase-test-timeout.patch
new file mode 100644
index 0000000000..c6aac6ac00
--- /dev/null
+++ b/gnu/packages/patches/nss-increase-test-timeout.patch
@@ -0,0 +1,25 @@
+We've seen some tests take more than 20s to complete on a busy armhf
+machine. Even a busy x86_64 machine can use more than 5s on some tests.
+
+Increase timeouts to increase chances of a successful build.
+
+--- a/nss/gtests/ssl_gtest/tls_connect.cc	2017-03-14 22:47:30.855813629 +0100
++++ b/nss/gtests/ssl_gtest/tls_connect.cc	2017-03-14 22:48:49.042335273 +0100
+@@ -245,7 +245,7 @@
+ 
+   ASSERT_TRUE_WAIT((client_->state() != TlsAgent::STATE_CONNECTING) &&
+                        (server_->state() != TlsAgent::STATE_CONNECTING),
+-                   5000);
++                   25000);
+ }
+ 
+ void TlsConnectTestBase::EnableExtendedMasterSecret() {
+@@ -387,7 +387,7 @@
+   } else {
+     fail_agent = server_;
+   }
+-  ASSERT_TRUE_WAIT(fail_agent->state() == TlsAgent::STATE_ERROR, 5000);
++  ASSERT_TRUE_WAIT(fail_agent->state() == TlsAgent::STATE_ERROR, 25000);
+ }
+ 
+ void TlsConnectTestBase::ConfigureVersion(uint16_t version) {