diff --git a/ChangeLog b/ChangeLog
index 6065d08b5..751fbfd32 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2015-09-01 Niels Grewe <niels.grewe@halbordnung.de>
+
+	* Source/NSRegularExpression.m: Fix handling of empty capture groups.
+
 2015-08-30  Richard Frith-Macdonald <rfm@gnu.org>
 
 	* Source/NSOperation.m: Fix potential deadlock with adding observers.
diff --git a/Source/NSRegularExpression.m b/Source/NSRegularExpression.m
index df0cd12b3..3c4de5183 100644
--- a/Source/NSRegularExpression.m
+++ b/Source/NSRegularExpression.m
@@ -297,8 +297,18 @@ prepareResult(NSRegularExpression *regex,
 
   for (i = 0; i < groups; i++)
     {
-      NSUInteger start = uregex_start(r, i, s);
-      NSUInteger end = uregex_end(r, i, s);
+      NSInteger start = uregex_start(r, i, s);
+      NSInteger end = uregex_end(r, i, s);
+      // The ICU API defines -1 as not found. Convert to
+      // NSNotFound if applicable.
+      if (start == -1)
+        {
+          start = NSNotFound;
+        }
+      if (end == -1)
+        {
+          end = NSNotFound;
+        }
 
       if (end < start)
         {