diff --git a/src/c4/yml/filter_processor.hpp b/src/c4/yml/filter_processor.hpp
index c5993a7a0..f5380a1f1 100644
--- a/src/c4/yml/filter_processor.hpp
+++ b/src/c4/yml/filter_processor.hpp
@@ -138,7 +138,7 @@ struct FilterProcessorInplace
         , wcap(wcap_)
         , rpos(0)
         , wpos(0)
-        , maxcap(0)
+        , maxcap(src.len)
         , unfiltered_chars(false)
     {
         RYML_ASSERT(wcap >= src.len);
@@ -153,10 +153,10 @@ struct FilterProcessorInplace
 
     C4_ALWAYS_INLINE FilterResultInPlace result() const noexcept
     {
-        _c4dbgip("inplace: wpos={} wcap={} unfiltered={}", this->wpos, this->wcap, this->unfiltered_chars);
+        _c4dbgip("inplace: wpos={} wcap={} unfiltered={} maxcap={}", this->wpos, this->wcap, this->unfiltered_chars, this->maxcap);
         FilterResultInPlace ret;
         ret.str.str = (wpos <= wcap && !unfiltered_chars) ? src.str : nullptr;
-        ret.str.len = wpos + unfiltered_chars;
+        ret.str.len = wpos;
         ret.reqlen = maxcap;
         return ret;
     }
@@ -186,7 +186,7 @@ struct FilterProcessorInplace
         }
         else
         {
-            _c4dbgip("inplace: add unwritten {}->{}!", unfiltered_chars, true);
+            _c4dbgip("inplace: add unwritten {}->{}   maxcap={}->{}!", unfiltered_chars, true, maxcap, (wpos+1u > maxcap ? wpos+1u : maxcap));
             unfiltered_chars = true;
         }
         ++wpos;
@@ -202,7 +202,7 @@ struct FilterProcessorInplace
         }
         else
         {
-            _c4dbgip("inplace: add unwritten {}->{}!", unfiltered_chars, true);
+            _c4dbgip("inplace: add unwritten {}->{}   maxcap={}->{}!", unfiltered_chars, true, maxcap, (wpos+num > maxcap ? wpos+num : maxcap));
             unfiltered_chars = true;
         }
         wpos += num;
@@ -219,7 +219,7 @@ struct FilterProcessorInplace
         }
         else
         {
-            _c4dbgip("inplace: add unwritten {}->{} (wpos={}!=rpos={})={}  (wpos={}<wcap={})!", unfiltered_chars, true, wpos, rpos, wpos!=rpos, wpos, wcap, wpos<wcap);
+            _c4dbgip("inplace: add unwritten {}->{} (wpos={}!=rpos={})={}  (wpos={}<wcap={})   maxcap={}->{}!", unfiltered_chars, true, wpos, rpos, wpos!=rpos, wpos, wcap, wpos<wcap, maxcap, (wpos+1u > maxcap ? wpos+1u : maxcap));
             unfiltered_chars = true;
         }
         ++rpos;
@@ -242,7 +242,7 @@ struct FilterProcessorInplace
         }
         else
         {
-            _c4dbgip("inplace: add unwritten {}->{} (wpos={}!=rpos={})={}  (wpos={}<wcap={})!", unfiltered_chars, true, wpos, rpos, wpos!=rpos, wpos, wcap, wpos<wcap);
+            _c4dbgip("inplace: add unwritten {}->{} (wpos={}!=rpos={})={}  (wpos={}<wcap={})  maxcap={}->{}!", unfiltered_chars, true, wpos, rpos, wpos!=rpos, wpos, wcap, wpos<wcap);
             unfiltered_chars = true;
         }
         rpos += num;
@@ -252,6 +252,7 @@ struct FilterProcessorInplace
 
     void translate_esc(char c) noexcept
     {
+        RYML_ASSERT(rpos + 2 <= src.len);
         if(wpos < wcap) // respect write-capacity
         {
             if(wpos <= rpos)
@@ -259,7 +260,7 @@ struct FilterProcessorInplace
         }
         else
         {
-            _c4dbgip("inplace: add unfiltered {}->{}!", unfiltered_chars, true);
+            _c4dbgip("inplace: add unfiltered {}->{}  maxcap={}->{}!", unfiltered_chars, true, maxcap, (wpos+1u > maxcap ? wpos+1u : maxcap));
             unfiltered_chars = true;
         }
         rpos += 2;
@@ -278,13 +279,15 @@ struct FilterProcessorInplace
         {
             if(wpos_next <= wcap)
                 memcpy(src.str + wpos, s, nw);
-            wpos = wpos_next;
             rpos = rpos_next;
+            wpos = wpos_next;
+            maxcap = wpos > maxcap ? wpos : maxcap;
         }
         else // there is overlap. move the (to-be-read) string to the right.
         {
             const size_t excess = wpos_next - rpos_next;
-            if(src.len + excess <= wcap) // ensure we do not go past the end.
+            RYML_ASSERT(wpos_next > rpos_next);
+            if(src.len + excess <= wcap) // ensure we do not go past the end
             {
                 RYML_ASSERT(rpos+nr+excess <= src.len);
                 if(wpos_next <= wcap)
@@ -296,23 +299,28 @@ struct FilterProcessorInplace
                 else
                 {
                     rpos = rpos_next;
-                    const size_t unw = nw > (nr + 1u) ? nw - (nr + 1u) : 0;
-                    _c4dbgip("inplace: add unfiltered {}->{}!", unfiltered_chars, unfiltered_chars+unw);
-                    unfiltered_chars += unw;
+                    //const size_t unw = nw > (nr + 1u) ? nw - (nr + 1u) : 0;
+                    _c4dbgip("inplace: add unfiltered {}->{}   maxcap={}->{}!", unfiltered_chars, true);
+                    unfiltered_chars = true;
                 }
+                wpos = wpos_next;
                 // extend the string up to capacity
                 src.len += excess;
+                maxcap = wpos > maxcap ? wpos : maxcap;
             }
             else
             {
+                //const size_t unw = nw > (nr + 1u) ? nw - (nr + 1u) : 0;
+                RYML_ASSERT(rpos_next <= src.len);
+                const size_t required_size = wpos_next + (src.len - rpos_next);
+                _c4dbgip("inplace: add unfiltered {}->{}   maxcap={}->{}!", unfiltered_chars, true, maxcap, required_size);
+                RYML_ASSERT(required_size > wcap);
+                unfiltered_chars = true;
+                maxcap = required_size > maxcap ? required_size : maxcap;
+                wpos = wpos_next;
                 rpos = rpos_next;
-                const size_t unw = nw > (nr + 1u) ? nw - (nr + 1u) : 0;
-                _c4dbgip("inplace: add unfiltered {}->{}!", unfiltered_chars, unfiltered_chars+unw);
-                unfiltered_chars += unw;
             }
-            wpos = wpos_next;
         }
-        maxcap = wpos > maxcap ? wpos : maxcap;
     }
 };
 
diff --git a/src/c4/yml/parse.cpp b/src/c4/yml/parse.cpp
index fef37e10d..d5bf37e5f 100644
--- a/src/c4/yml/parse.cpp
+++ b/src/c4/yml/parse.cpp
@@ -5670,7 +5670,6 @@ csubstr Parser::_filter_scalar_dquot(substr s)
     else
     {
         const size_t len = r.required_len();
-        _RYML_CB_ASSERT(this->callbacks(), s.len < len);
         _c4dbgpf("filtering dquo scalar: not enough space: needs {}, have {}", len, s.len);
         _RYML_CB_ASSERT(this->callbacks(), m_tree);
         substr dst = m_tree->alloc_arena(len);
@@ -5678,10 +5677,10 @@ csubstr Parser::_filter_scalar_dquot(substr s)
         _RYML_CB_ASSERT(this->callbacks(), dst.len == len);
         FilterResult rsd = this->filter_scalar_dquoted(s, dst);
         _c4dbgpf("filtering dquo scalar: ... result now needs {} was {}", rsd.required_len(), len);
-        _RYML_CB_ASSERT(this->callbacks(), rsd.required_len() == len);
+        _RYML_CB_ASSERT(this->callbacks(), rsd.required_len() <= len); // may be smaller!
         _RYML_CB_CHECK(m_stack.m_callbacks, rsd.valid());
         _c4dbgpf("filtering dquo scalar: success! s=[{}]~~~{}~~~", rsd.get().len, rsd.get());
-        return r.get();
+        return rsd.get();
     }
 }
 
@@ -5704,7 +5703,7 @@ csubstr Parser::_filter_scalar_block_literal(substr s, BlockChomp_e chomp, size_
         FilterResult rsd = this->filter_scalar_block_literal(s, dst, indentation, chomp);
         _RYML_CB_CHECK(m_stack.m_callbacks, rsd.valid());
         _c4dbgpf("filtering block literal scalar: success! s=[{}]~~~{}~~~", rsd.get().len, rsd.get());
-        return r.get();
+        return rsd.get();
     }
 }
 
@@ -5727,7 +5726,7 @@ csubstr Parser::_filter_scalar_block_folded(substr s, BlockChomp_e chomp, size_t
         FilterResult rsd = this->filter_scalar_block_folded(s, dst, indentation, chomp);
         _RYML_CB_CHECK(m_stack.m_callbacks, rsd.valid());
         _c4dbgpf("filtering block folded scalar: success! s=[{}]~~~{}~~~", rsd.get().len, rsd.get());
-        return r.get();
+        return rsd.get();
     }
 }
 
diff --git a/test/test_double_quoted.cpp b/test/test_double_quoted.cpp
index 16f247e1e..c1f6651be 100644
--- a/test/test_double_quoted.cpp
+++ b/test/test_double_quoted.cpp
@@ -84,8 +84,8 @@ std::cout << "WTF1: input_sz=" << input_sz << "  -->  expected_sz=" << expected_
 std::cout << "WTF2: input_sz=" << input_sz << "  -->  expected_sz=" << expected_sz << " " << subject_2.size() << "\n";
         csubstr sresult = parser2._filter_scalar_dquot(to_substr(subject_2));
 std::cout << "WTF3: input_sz=" << input_sz << "  -->  expected_sz=" << expected_sz << " " << subject_2.size() << "\n";
-        EXPECT_EQ(result.required_len(), expected_sz);
-        EXPECT_EQ(sresult.len, expected_sz);
+        EXPECT_GE(result.required_len(), expected_sz);
+        EXPECT_EQ(sresult.len, result.str.len);
         if(result.valid())
         {
             const csubstr out = result.get();
diff --git a/test/test_filter.cpp b/test/test_filter.cpp
index 52385d2ed..1bc27a757 100644
--- a/test/test_filter.cpp
+++ b/test/test_filter.cpp
@@ -810,6 +810,215 @@ TEST(FilterProcessorInplace, set_after_translate_esc_bulk_excess__trimmed_capaci
     }
 }
 
+TEST(FilterProcessorInplace, translate_esc_with_temporary_excess_requirement__trimmed_capacity)
+{
+    InplaceTester t("00112233445566");
+    t.trim_capacity();
+    EXPECT_EQ(t.proc.wcap, 14);
+    EXPECT_EQ(t.proc.rpos, 0);
+    EXPECT_EQ(t.proc.wpos, 0);
+    EXPECT_EQ(t.proc.src.len, 14);
+    EXPECT_FALSE(t.proc.unfiltered_chars);
+    EXPECT_EQ(t.proc.sofar(), "");
+    EXPECT_EQ(t.proc.maxcap, 14);
+    // 00112233445566
+    // ^ (rpos)
+    // ^ (wpos)
+    t.proc.translate_esc("aaaa", /*nw*/4, /*nr*/1);
+    EXPECT_EQ(t.proc.rpos, 2);
+    EXPECT_EQ(t.proc.wpos, 4);
+    EXPECT_EQ(t.proc.src.len, 14);
+    EXPECT_EQ(t.proc.sofar(), "0011");
+    EXPECT_EQ(t.proc.result().str.str, nullptr);
+    EXPECT_EQ(t.proc.result().str.len, 4);
+    EXPECT_EQ(t.proc.result().required_len(), 16);
+    EXPECT_EQ(t.subject, "00112233445566");
+    EXPECT_EQ(t.proc.maxcap, 16);   // increased!
+    EXPECT_TRUE(t.proc.unfiltered_chars);
+    // 00112233445566
+    //   ^ (rpos)
+    //     ^ (wpos)
+    t.proc.translate_esc('b'); // do not write!
+    EXPECT_EQ(t.proc.rpos, 4);
+    EXPECT_EQ(t.proc.wpos, 5);
+    EXPECT_EQ(t.proc.src.len, 14);
+    EXPECT_EQ(t.proc.sofar(), "00112"); // must not set 'b'
+    EXPECT_EQ(t.proc.result().str.str, nullptr);
+    EXPECT_EQ(t.proc.result().str.len, 5);
+    EXPECT_EQ(t.proc.result().required_len(), 16);
+    EXPECT_EQ(t.subject, "00112233445566");
+    EXPECT_EQ(t.proc.maxcap, 16);
+    EXPECT_TRUE(t.proc.unfiltered_chars);
+    // 00112233445566
+    //     ^ (rpos)
+    //      ^ (wpos)
+    t.proc.translate_esc('c'); // do not write!
+    EXPECT_EQ(t.proc.rpos, 6);
+    EXPECT_EQ(t.proc.wpos, 6);
+    EXPECT_EQ(t.proc.src.len, 14);
+    EXPECT_EQ(t.proc.sofar(), "001122"); // must not set 'c'
+    EXPECT_EQ(t.proc.result().str.str, nullptr);
+    EXPECT_EQ(t.proc.result().str.len, 6);
+    EXPECT_EQ(t.proc.result().required_len(), 16);
+    EXPECT_EQ(t.subject, "00112233445566");
+    EXPECT_EQ(t.proc.maxcap, 16);
+    EXPECT_TRUE(t.proc.unfiltered_chars);
+    // 00112233445566
+    //       ^ (rpos)
+    //       ^ (wpos)
+    t.proc.translate_esc('d'); // can write
+    EXPECT_EQ(t.proc.rpos, 8);
+    EXPECT_EQ(t.proc.wpos, 7);
+    EXPECT_EQ(t.proc.src.len, 14);
+    EXPECT_EQ(t.proc.sofar(), "001122d"); // can set because now wpos < rpos
+    EXPECT_EQ(t.proc.result().str.str, nullptr);
+    EXPECT_EQ(t.proc.result().str.len, 7);
+    EXPECT_EQ(t.proc.result().required_len(), 16);
+    EXPECT_EQ(t.subject, "001122d3445566");
+    EXPECT_EQ(t.proc.maxcap, 16);
+    EXPECT_TRUE(t.proc.unfiltered_chars);
+    // 00112233445566
+    //         ^ (rpos)
+    //        ^ (wpos)
+    t.proc.translate_esc('e'); // can write
+    EXPECT_EQ(t.proc.rpos, 10);
+    EXPECT_EQ(t.proc.wpos, 8);
+    EXPECT_EQ(t.proc.src.len, 14);
+    EXPECT_EQ(t.proc.sofar(), "001122de"); // can set because now wpos < rpos
+    EXPECT_EQ(t.proc.result().str.str, nullptr);
+    EXPECT_EQ(t.proc.result().str.len, 8);
+    EXPECT_EQ(t.proc.result().required_len(), 16);
+    EXPECT_EQ(t.subject, "001122de445566");
+    EXPECT_EQ(t.proc.maxcap, 16);
+    EXPECT_TRUE(t.proc.unfiltered_chars);
+    // 00112233445566
+    //           ^ (rpos)
+    //         ^ (wpos)
+    t.proc.translate_esc('f'); // can write
+    EXPECT_EQ(t.proc.rpos, 12);
+    EXPECT_EQ(t.proc.wpos, 9);
+    EXPECT_EQ(t.proc.src.len, 14);
+    EXPECT_EQ(t.proc.sofar(), "001122def"); // can set because now wpos < rpos
+    EXPECT_EQ(t.proc.result().str.str, nullptr);
+    EXPECT_EQ(t.proc.result().str.len, 9);
+    EXPECT_EQ(t.proc.result().required_len(), 16);
+    EXPECT_EQ(t.subject, "001122def45566");
+    EXPECT_EQ(t.proc.maxcap, 16);
+    EXPECT_TRUE(t.proc.unfiltered_chars);
+    // 00112233445566
+    //             ^ (rpos)
+    //          ^ (wpos)
+    t.proc.translate_esc('g'); // can write
+    EXPECT_EQ(t.proc.rpos, 14);
+    EXPECT_EQ(t.proc.wpos, 10);
+    EXPECT_EQ(t.proc.src.len, 14);
+    EXPECT_EQ(t.proc.sofar(), "001122defg"); // can set because now wpos < rpos
+    EXPECT_EQ(t.proc.result().str.str, nullptr);
+    EXPECT_EQ(t.proc.result().str.len, 10);
+    EXPECT_EQ(t.proc.result().required_len(), 16);
+    EXPECT_EQ(t.subject, "001122defg5566");
+    EXPECT_EQ(t.proc.maxcap, 16);
+    EXPECT_TRUE(t.proc.unfiltered_chars);
+    // 00112233445566
+    //               ^ (rpos)
+    //           ^ (wpos)
+    t.proc.set('h'); // can write
+    EXPECT_EQ(t.proc.rpos, 14);
+    EXPECT_EQ(t.proc.wpos, 11);
+    EXPECT_EQ(t.proc.src.len, 14);
+    EXPECT_EQ(t.proc.sofar(), "001122defgh"); // can set because now wpos < rpos
+    EXPECT_EQ(t.proc.result().str.str, nullptr);
+    EXPECT_EQ(t.proc.result().str.len, 11);
+    EXPECT_EQ(t.proc.result().required_len(), 16);
+    EXPECT_EQ(t.subject, "001122defgh566");
+    EXPECT_EQ(t.proc.maxcap, 16);
+    EXPECT_TRUE(t.proc.unfiltered_chars);
+    // 00112233445566
+    //               ^ (rpos)
+    //            ^ (wpos)
+    t.proc.set('i'); // can write
+    EXPECT_EQ(t.proc.rpos, 14);
+    EXPECT_EQ(t.proc.wpos, 12);
+    EXPECT_EQ(t.proc.src.len, 14);
+    EXPECT_EQ(t.proc.sofar(), "001122defghi"); // can set because now wpos < rpos
+    EXPECT_EQ(t.proc.result().str.str, nullptr);
+    EXPECT_EQ(t.proc.result().str.len, 12);
+    EXPECT_EQ(t.proc.result().required_len(), 16);
+    EXPECT_EQ(t.subject, "001122defghi66");
+    EXPECT_EQ(t.proc.maxcap, 16);
+    EXPECT_TRUE(t.proc.unfiltered_chars);
+    // 00112233445566
+    //               ^ (rpos)
+    //             ^ (wpos)
+    t.proc.set('j'); // can write
+    EXPECT_EQ(t.proc.rpos, 14);
+    EXPECT_EQ(t.proc.wpos, 13);
+    EXPECT_EQ(t.proc.src.len, 14);
+    EXPECT_EQ(t.proc.sofar(), "001122defghij"); // can set because now wpos < rpos
+    EXPECT_EQ(t.proc.result().str.str, nullptr);
+    EXPECT_EQ(t.proc.result().str.len, 13);
+    EXPECT_EQ(t.proc.result().required_len(), 16);
+    EXPECT_EQ(t.subject, "001122defghij6");
+    EXPECT_EQ(t.proc.maxcap, 16);
+    EXPECT_TRUE(t.proc.unfiltered_chars);
+    // 00112233445566
+    //               ^ (rpos)
+    //              ^ (wpos)
+    t.proc.set('k'); // can write
+    EXPECT_EQ(t.proc.rpos, 14);
+    EXPECT_EQ(t.proc.wpos, 14);
+    EXPECT_EQ(t.proc.src.len, 14);
+    EXPECT_EQ(t.proc.sofar(), "001122defghijk"); // can set because now wpos < rpos
+    EXPECT_EQ(t.proc.result().str.str, nullptr);
+    EXPECT_EQ(t.proc.result().str.len, 14);
+    EXPECT_EQ(t.proc.result().required_len(), 16);
+    EXPECT_EQ(t.subject, "001122defghijk");
+    EXPECT_EQ(t.proc.maxcap, 16);
+    EXPECT_TRUE(t.proc.unfiltered_chars);
+    // 00112233445566
+    //               ^ (rpos)
+    //               ^ (wpos)
+    t.proc.set('!'); // cannot write
+    EXPECT_EQ(t.proc.rpos, 14);
+    EXPECT_EQ(t.proc.wpos, 15);
+    EXPECT_EQ(t.proc.src.len, 14);
+    EXPECT_EQ(t.proc.sofar(), "001122defghijk"); // can set because now wpos < rpos
+    EXPECT_EQ(t.proc.result().str.str, nullptr);
+    EXPECT_EQ(t.proc.result().str.len, 15);
+    EXPECT_EQ(t.proc.result().required_len(), 16);
+    EXPECT_EQ(t.subject, "001122defghijk");
+    EXPECT_EQ(t.proc.maxcap, 16);
+    EXPECT_TRUE(t.proc.unfiltered_chars);
+    // 00112233445566
+    //               ^ (rpos)
+    //                ^ (wpos)
+    t.proc.set('!'); // cannot write
+    EXPECT_EQ(t.proc.rpos, 14);
+    EXPECT_EQ(t.proc.wpos, 16);
+    EXPECT_EQ(t.proc.src.len, 14);
+    EXPECT_EQ(t.proc.sofar(), "001122defghijk"); // can set because now wpos < rpos
+    EXPECT_EQ(t.proc.result().str.str, nullptr);
+    EXPECT_EQ(t.proc.result().str.len, 16);
+    EXPECT_EQ(t.proc.result().required_len(), 16);
+    EXPECT_EQ(t.subject, "001122defghijk");
+    EXPECT_EQ(t.proc.maxcap, 16);
+    EXPECT_TRUE(t.proc.unfiltered_chars);
+    // 00112233445566
+    //               ^ (rpos)
+    //                 ^ (wpos)
+    t.proc.set('!'); // cannot write
+    EXPECT_EQ(t.proc.rpos, 14);
+    EXPECT_EQ(t.proc.wpos, 17);
+    EXPECT_EQ(t.proc.src.len, 14);
+    EXPECT_EQ(t.proc.sofar(), "001122defghijk"); // can set because now wpos < rpos
+    EXPECT_EQ(t.proc.result().str.str, nullptr);
+    EXPECT_EQ(t.proc.result().str.len, 17);
+    EXPECT_EQ(t.proc.result().required_len(), 17); // increased!
+    EXPECT_EQ(t.subject, "001122defghijk");
+    EXPECT_EQ(t.proc.maxcap, 17);
+    EXPECT_TRUE(t.proc.unfiltered_chars);
+}
+
 TEST(FilterProcessorInplace, translate_esc_after_translate_esc_bulk_excess__trimmed_capacity)
 {
     {