diff --git a/src/common/datetimefmt.cpp b/src/common/datetimefmt.cpp
index 9da429c7c8..1dfdd1b45f 100644
--- a/src/common/datetimefmt.cpp
+++ b/src/common/datetimefmt.cpp
@@ -751,7 +751,7 @@ wxDateTime::ParseRfc822Date(const wxString& originalDate, wxString::const_iterat
     // to the date string (32 being the length of a typical RFC822 timestamp).
     const wxString date(originalDate + wxString(32, '\0'));
 
-    const wxString::const_iterator pEnd = date.end();
+    const wxString::const_iterator pEnd = date.begin() + originalDate.length();
     wxString::const_iterator p = date.begin();
 
     // 1. week day (optional)
@@ -896,7 +896,8 @@ wxDateTime::ParseRfc822Date(const wxString& originalDate, wxString::const_iterat
         // the explicit offset given: it has the form of hhmm
         bool plus = *p++ == '+';
 
-        if ( !wxIsdigit(*p) || !wxIsdigit(*(p + 1)) )
+        if ( p == pEnd || !wxIsdigit(*p) ||
+             p + 1 == pEnd || !wxIsdigit(*(p + 1)) )
             return false;
 
 
@@ -905,7 +906,8 @@ wxDateTime::ParseRfc822Date(const wxString& originalDate, wxString::const_iterat
 
         p += 2;
 
-        if ( !wxIsdigit(*p) || !wxIsdigit(*(p + 1)) )
+        if ( p == pEnd || !wxIsdigit(*p) ||
+             p + 1 == pEnd || !wxIsdigit(*(p + 1)) )
             return false;
 
         // minutes
@@ -920,7 +922,7 @@ wxDateTime::ParseRfc822Date(const wxString& originalDate, wxString::const_iterat
     {
         // the symbolic timezone given: may be either military timezone or one
         // of standard abbreviations
-        if ( !*(p + 1) )
+        if ( p + 1 == pEnd )
         {
             // military: Z = UTC, J unused, A = -1, ..., Y = +12
             static const int offsets[26] =
@@ -939,7 +941,7 @@ wxDateTime::ParseRfc822Date(const wxString& originalDate, wxString::const_iterat
         else
         {
             // abbreviation
-            const wxString tz(p, date.end());
+            const wxString tz(p, pEnd);
             if ( tz == wxT("UT") || tz == wxT("UTC") || tz == wxT("GMT") )
                 offset = 0;
             else if ( tz == wxT("AST") )
diff --git a/tests/datetime/datetimetest.cpp b/tests/datetime/datetimetest.cpp
index 9f48a82245..9a48b3a781 100644
--- a/tests/datetime/datetimetest.cpp
+++ b/tests/datetime/datetimetest.cpp
@@ -1106,6 +1106,18 @@ void DateTimeTestCase::TestParseRFC822()
             true
         },
 
+        {
+            "Sat, 18 Dec 1999 10:48:30 G", // military time zone
+            { 18, wxDateTime::Dec, 1999, 17, 48, 30 },
+            true
+        },
+
+        {
+            "Sat, 18 Dec 1999 10:48:30 Q", // military time zone
+            { 18, wxDateTime::Dec, 1999,  6, 48, 30 },
+            true
+        },
+
         // seconds are optional according to the RFC
         {
             "Sun, 01 Jun 2008 16:30 +0200",
@@ -1159,12 +1171,30 @@ void DateTimeTestCase::TestParseRFC822()
             false
         },
 
+        {
+            "Sun, 01 Jun 2008 16:39:10 +020", // truncated time zone
+            { 0 },
+            false
+        },
+
         {
             "Sun, 01 Jun 2008 16:39:10 +02", // truncated time zone
             { 0 },
             false
         },
 
+        {
+            "Sun, 01 Jun 2008 16:39:10 +0", // truncated time zone
+            { 0 },
+            false
+        },
+
+        {
+            "Sun, 01 Jun 2008 16:39:10 +", // truncated time zone
+            { 0 },
+            false
+        },
+
         {
             "Sun, 01 Jun 2008 16:39:10 GM", // truncated time zone
             { 0 },