diff --git a/nsprpub/patches/README.TXT b/nsprpub/patches/README.TXT
new file mode 100644
index 0000000000000..38fecbaba0e69
--- /dev/null
+++ b/nsprpub/patches/README.TXT
@@ -0,0 +1,9 @@
+bug1399100-temporary.patch :
+  This is a temporary patch as described in
+    https://bugzilla.mozilla.org/show_bug.cgi?id=1399100
+  It is temporarily necessary because of the changes in
+    https://bugzilla.mozilla.org/show_bug.cgi?id=1384633
+  The patch should be re-applied during the Firefox 57 release cycle,
+  if other changes to NSPR are necessary during the lifetime of Firefox 57.
+  The temporary API will be removed for Firefox 58, as agreed in
+    https://bugzilla.mozilla.org/show_bug.cgi?id=1394808
diff --git a/nsprpub/patches/bug1399100-temporary.patch b/nsprpub/patches/bug1399100-temporary.patch
new file mode 100644
index 0000000000000..744d747cb0cdf
--- /dev/null
+++ b/nsprpub/patches/bug1399100-temporary.patch
@@ -0,0 +1,16 @@
+diff --git a/nsprpub/pr/src/nspr.def b/nsprpub/pr/src/nspr.def
+--- a/nsprpub/pr/src/nspr.def
++++ b/nsprpub/pr/src/nspr.def
+@@ -457,8 +457,12 @@ EXPORTS ;-
+ ;+} NSPR_4.9.2;
+ ;+# Function PR_DuplicateEnvironment had been added in NSPR 4.10.9,
+ ;+# but we neglected to add it to nspr.def until NSPR 4.12
+ ;+NSPR_4.12 {
+ ;+      global:
+ 		PR_DuplicateEnvironment;
+ 		PR_GetEnvSecure;
+ ;+} NSPR_4.10.3;
++;+NSPR_4.17_fork {
++;+      global:
++		PR_EXPERIMENTAL_ONLY_IN_4_17_GetOverlappedIOHandle;
++;+} NSPR_4.16;
diff --git a/nsprpub/pr/src/nspr.def b/nsprpub/pr/src/nspr.def
index 726979ba9dee5..16e526f573776 100644
--- a/nsprpub/pr/src/nspr.def
+++ b/nsprpub/pr/src/nspr.def
@@ -462,3 +462,7 @@ EXPORTS ;-
 		PR_DuplicateEnvironment;
 		PR_GetEnvSecure;
 ;+} NSPR_4.10.3;
+;+NSPR_4.17_fork {
+;+      global:
+		PR_EXPERIMENTAL_ONLY_IN_4_17_GetOverlappedIOHandle;
+;+} NSPR_4.16;