diff --git a/nsprpub/configure b/nsprpub/configure
index fa0ab20b114..15d1cfa0406 100755
--- a/nsprpub/configure
+++ b/nsprpub/configure
@@ -5378,6 +5378,7 @@ lib/ds/Makefile
 lib/libc/Makefile 
 lib/libc/include/Makefile 
 lib/libc/src/Makefile 
+lib/tests/Makefile
 pr/Makefile 
 pr/include/Makefile 
 pr/include/md/Makefile 
diff --git a/nsprpub/configure.in b/nsprpub/configure.in
index e3d16de5f81..56f20ab69e1 100644
--- a/nsprpub/configure.in
+++ b/nsprpub/configure.in
@@ -2256,6 +2256,7 @@ lib/ds/Makefile
 lib/libc/Makefile 
 lib/libc/include/Makefile 
 lib/libc/src/Makefile 
+lib/tests/Makefile
 pr/Makefile 
 pr/include/Makefile 
 pr/include/md/Makefile 
diff --git a/nsprpub/lib/libc/include/plstr.h b/nsprpub/lib/libc/include/plstr.h
index b619a934aeb..551567e4940 100644
--- a/nsprpub/lib/libc/include/plstr.h
+++ b/nsprpub/lib/libc/include/plstr.h
@@ -18,6 +18,7 @@
  * Rights Reserved.
  * 
  * Contributor(s):
+ *   Roland Mainz <roland mainz@informatik.med.uni-giessen.de>
  * 
  * Alternatively, the contents of this file may be used under the
  * terms of the GNU General Public License Version 2 or later (the
@@ -434,7 +435,29 @@ PR_EXTERN(char *)
 PL_strncaserstr(const char *big, const char *little, PRUint32 max);
 
 /*
- * Things not (yet?) included: strspn/strcspn, strtok/strtok_r, strsep.
+ * PL_strtok_r
+ *
+ * Splits the string s1 into tokens, separated by one or more characters
+ * from the separator string s2.  The argument lasts points to a
+ * user-supplied char * pointer in which PL_strtok_r stores information
+ * for it to continue scanning the same string.
+ *
+ * In the first call to PL_strtok_r, s1 points to a string and the value
+ * of *lasts is ignored.  PL_strtok_r returns a pointer to the first
+ * token, writes '\0' into the character following the first token, and
+ * updates *lasts.
+ *
+ * In subsequent calls, s1 is null and lasts must stay unchanged from the
+ * previous call.  The separator string s2 may be different from call to
+ * call.  PL_strtok_r returns a pointer to the next token in s1.  When no
+ * token remains in s1, PL_strtok_r returns null.
+ */
+
+PR_EXTERN(char *)
+PL_strtok_r(char *s1, const char *s2, char **lasts);
+
+/*
+ * Things not (yet?) included: strspn/strcspn, strsep.
  * memchr, memcmp, memcpy, memccpy, index, rindex, bcmp, bcopy, bzero.
  * Any and all i18n/l10n stuff.
  */
diff --git a/nsprpub/lib/libc/src/Makefile.in b/nsprpub/lib/libc/src/Makefile.in
index d79b9c9a60f..2977399e81f 100644
--- a/nsprpub/lib/libc/src/Makefile.in
+++ b/nsprpub/lib/libc/src/Makefile.in
@@ -57,6 +57,7 @@ CSRCS =\
 	strpbrk.c \
 	strstr.c  \
 	strcstr.c \
+	strtok.c  \
 	base64.c \
 	plerror.c \
 	plgetopt.c \
diff --git a/nsprpub/lib/libc/src/strtok.c b/nsprpub/lib/libc/src/strtok.c
new file mode 100644
index 00000000000..243a8981b43
--- /dev/null
+++ b/nsprpub/lib/libc/src/strtok.c
@@ -0,0 +1,86 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 
+ * The contents of this file are subject to the Mozilla Public
+ * License Version 1.1 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of
+ * the License at http://www.mozilla.org/MPL/
+ * 
+ * Software distributed under the License is distributed on an "AS
+ * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
+ * implied. See the License for the specific language governing
+ * rights and limitations under the License.
+ * 
+ * The Original Code is the Netscape Portable Runtime (NSPR).
+ * 
+ * The Initial Developer of the Original Code is Netscape
+ * Communications Corporation.  Portions created by Netscape are 
+ * Copyright (C) 2001 Netscape Communications Corporation.  All
+ * Rights Reserved.
+ * 
+ * Contributor(s):
+ *   Roland Mainz <roland mainz@informatik.med.uni-giessen.de>
+ * 
+ * Alternatively, the contents of this file may be used under the
+ * terms of the GNU General Public License Version 2 or later (the
+ * "GPL"), in which case the provisions of the GPL are applicable 
+ * instead of those above.  If you wish to allow use of your 
+ * version of this file only under the terms of the GPL and not to
+ * allow others to use your version of this file under the MPL,
+ * indicate your decision by deleting the provisions above and
+ * replace them with the notice and other provisions required by
+ * the GPL.  If you do not delete the provisions above, a recipient
+ * may use your version of this file under either the MPL or the
+ * GPL.
+ */
+
+#include "plstr.h"
+
+PR_IMPLEMENT(char *)
+PL_strtok_r(char *s1, const char *s2, char **lasts)
+{
+    const char *sepp;
+    int         c, sc;
+    char       *tok;
+
+    if( s1 == NULL )
+    {
+        if( *lasts == NULL )
+            return NULL;
+
+        s1 = *lasts;
+    }
+  
+    for( ; (c = *s1) != 0; s1++ )
+    {
+        for( sepp = s2 ; (sc = *sepp) != 0 ; sepp++ )
+        {
+            if( c == sc )
+                break;
+        }
+        if( sc == 0 )
+            break; 
+    }
+
+    if( c == 0 )
+    {
+        *lasts = NULL;
+        return NULL;
+    }
+  
+    tok = s1++;
+
+    for( ; (c = *s1) != 0; s1++ )
+    {
+        for( sepp = s2; (sc = *sepp) != 0; sepp++ )
+        {
+            if( c == sc )
+            {
+                *s1++ = '\0';
+                *lasts = s1;
+                return tok;
+            }
+        }
+    }
+    *lasts = NULL;
+    return tok;
+}
diff --git a/nsprpub/lib/tests/string.c b/nsprpub/lib/tests/string.c
index 895189c3ace..0e2c3a55491 100644
--- a/nsprpub/lib/tests/string.c
+++ b/nsprpub/lib/tests/string.c
@@ -3003,6 +3003,59 @@ PRBool test_030(void)
     return PR_TRUE;
 }
 
+/* PL_strtok_r */
+PRBool test_031(void)
+{
+    static const char *tokens[] = {
+        "wtc", "relyea", "nelsonb", "jpierre", "nicolson",
+        "ian.mcgreer", "kirk.erickson", "sonja.mirtitsch", "mhein"
+    };
+
+    static const char *seps[] = {
+        ", ", ",", " ", "\t", ",,,", " ,", "    ", " \t\t", ","
+    };
+
+    static const char s2[] = ", \t";
+
+    char string[ 1024 ];
+    char *s1;
+    char *token;
+    char *lasts;
+    unsigned int i;
+
+    printf("Test 031 (PL_strtok_r)    ..."); fflush(stdout);
+
+    /* Build the string. */
+    string[0] = '\0';
+    for( i = 0; i < sizeof(tokens)/sizeof(tokens[0]); i++ )
+    {
+        PL_strcat(string, tokens[i]);
+        PL_strcat(string, seps[i]);
+    }
+    
+    /* Scan the string for tokens. */
+    i = 0;
+    s1 = string;
+    while( (token = PL_strtok_r(s1, s2, &lasts)) != NULL)
+    {
+        if( strcmp(token, tokens[i]) != 0 )
+        {
+            printf("FAIL wrong token scanned\n");
+            return PR_FALSE;
+        }
+        i++;
+        s1 = NULL;
+    }
+    if( i != sizeof(tokens)/sizeof(tokens[0]) )
+    {
+        printf("FAIL wrong number of tokens scanned\n");
+        return PR_FALSE;
+    }
+
+    printf("PASS\n");
+    return PR_TRUE;
+}
+
 int
 main
 (
@@ -3044,6 +3097,7 @@ main
         && test_028()
         && test_029()
         && test_030()
+        && test_031()
       )
     {
         printf("Suite passed.\n");