diff --git a/src/common/stringops.cpp b/src/common/stringops.cpp
index 1592706872..36ff4045a4 100644
--- a/src/common/stringops.cpp
+++ b/src/common/stringops.cpp
@@ -94,7 +94,7 @@ bool wxStringOperationsUtf8::IsValidUtf8String(const char *str, size_t len)
     const unsigned char *c = (const unsigned char*)str;
     const unsigned char * const end = (len == wxStringImpl::npos) ? NULL : c + len;
 
-    for ( ; c != end && *c; ++c )
+    for ( ; end != NULL ? c != end : *c; ++c )
     {
         unsigned char b = *c;
 
diff --git a/tests/strings/unicode.cpp b/tests/strings/unicode.cpp
index 20751f23fe..19587dd99f 100644
--- a/tests/strings/unicode.cpp
+++ b/tests/strings/unicode.cpp
@@ -364,6 +364,14 @@ void UnicodeTestCase::ConversionUTF8()
     CPPUNIT_ASSERT_EQUAL( 0, c.ToWChar(NULL, 0, u25a6, 0) );
     CPPUNIT_ASSERT_EQUAL( 1, c.ToWChar(NULL, 0, u25a6, 3) );
     CPPUNIT_ASSERT_EQUAL( 2, c.ToWChar(NULL, 0, u25a6, 4) );
+
+    // Verify that converting a string with embedded NULs works.
+    CPPUNIT_ASSERT_EQUAL( 5, wxString::FromUTF8("abc\0\x32", 5).length() );
+
+    // Verify that converting a string containing invalid UTF-8 does not work,
+    // even if it happens after an embedded NUL.
+    CPPUNIT_ASSERT( wxString::FromUTF8("abc\xff").empty() );
+    CPPUNIT_ASSERT( wxString::FromUTF8("abc\0\xff", 5).empty() );
 }
 
 void UnicodeTestCase::ConversionUTF16()