diff --git a/src/c4/yml/filter_processor.hpp b/src/c4/yml/filter_processor.hpp
index f5380a1f..f08ee79c 100644
--- a/src/c4/yml/filter_processor.hpp
+++ b/src/c4/yml/filter_processor.hpp
@@ -181,7 +181,7 @@ struct FilterProcessorInplace
     {
         if(wpos < wcap)  // respect write-capacity
         {
-            if(wpos <= rpos)
+            if((wpos <= rpos) && !unfiltered_chars)
                 src.str[wpos] = c;
         }
         else
@@ -197,7 +197,7 @@ struct FilterProcessorInplace
         RYML_ASSERT(num);
         if(wpos + num <= wcap)  // respect write-capacity
         {
-            if(wpos <= rpos)
+            if((wpos <= rpos) && !unfiltered_chars)
                 memset(src.str + wpos, c, num);
         }
         else
@@ -214,7 +214,7 @@ struct FilterProcessorInplace
         RYML_ASSERT(rpos < src.len);
         if(wpos < wcap)  // respect write-capacity
         {
-            if(wpos < rpos)  // write only if wpos is behind rpos
+            if((wpos < rpos) && !unfiltered_chars)  // write only if wpos is behind rpos
                 src.str[wpos] = src.str[rpos];
         }
         else
@@ -232,7 +232,7 @@ struct FilterProcessorInplace
         RYML_ASSERT(rpos+num <= src.len);
         if(wpos + num <= wcap)  // respect write-capacity
         {
-            if(wpos < rpos)  // write only if wpos is behind rpos
+            if((wpos < rpos) && !unfiltered_chars)  // write only if wpos is behind rpos
             {
                 if(wpos + num <= rpos) // there is no overlap
                     memcpy(src.str + wpos, src.str + rpos, num);
@@ -255,7 +255,7 @@ struct FilterProcessorInplace
         RYML_ASSERT(rpos + 2 <= src.len);
         if(wpos < wcap) // respect write-capacity
         {
-            if(wpos <= rpos)
+            if((wpos <= rpos) && !unfiltered_chars)
                 src.str[wpos] = c;
         }
         else
@@ -277,7 +277,7 @@ struct FilterProcessorInplace
         const size_t rpos_next = rpos + nr + 1u; // add 1u to account for the escape character
         if(wpos_next <= rpos_next) // read and write do not overlap. just do a vanilla copy.
         {
-            if(wpos_next <= wcap)
+            if((wpos_next <= wcap) && !unfiltered_chars)
                 memcpy(src.str + wpos, s, nw);
             rpos = rpos_next;
             wpos = wpos_next;
@@ -292,8 +292,11 @@ struct FilterProcessorInplace
                 RYML_ASSERT(rpos+nr+excess <= src.len);
                 if(wpos_next <= wcap)
                 {
-                    memmove(src.str + wpos_next, src.str + rpos_next, src.len - rpos_next);
-                    memcpy(src.str + wpos, s, nw);
+                    if(!unfiltered_chars)
+                    {
+                        memmove(src.str + wpos_next, src.str + rpos_next, src.len - rpos_next);
+                        memcpy(src.str + wpos, s, nw);
+                    }
                     rpos = wpos_next; // wpos, not rpos
                 }
                 else
@@ -313,7 +316,7 @@ struct FilterProcessorInplace
                 //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);
+                _c4dbgip("inplace: add unfiltered {}->{}   maxcap={}->{}!", unfiltered_chars, true, maxcap, required_size > maxcap ? required_size : maxcap);
                 RYML_ASSERT(required_size > wcap);
                 unfiltered_chars = true;
                 maxcap = required_size > maxcap ? required_size : maxcap;
diff --git a/src/c4/yml/parse.cpp b/src/c4/yml/parse.cpp
index d5bf37e5..3dc36884 100644
--- a/src/c4/yml/parse.cpp
+++ b/src/c4/yml/parse.cpp
@@ -4787,7 +4787,7 @@ FilterResultInPlace Parser::filter_scalar_squoted_in_place(substr dst, size_t ca
 /* double quoted */
 
 // a debugging scaffold:
-#if 0
+#if 1
 #define _c4dbgfdq(fmt, ...) _c4dbgpf("filt_dquo[{}->{}]: " fmt, proc.rpos, proc.wpos, __VA_ARGS__)
 #else
 #define _c4dbgfdq(...)
@@ -4992,6 +4992,10 @@ void Parser::_filter_dquoted_backslash(FilterProcessor &C4_RESTRICT proc)
     {
         proc.skip();
     }
+    else
+    {
+        _c4err("unknown character '{}' after '\\' pos={}", _c4prc(next), proc.rpos);
+    }
     _c4dbgfdq("backslash...sofar=[{}]~~~{}~~~", proc.wpos, proc.sofar());
 }
 
diff --git a/test/test_filter.cpp b/test/test_filter.cpp
index 1bc27a75..e7d28b5b 100644
--- a/test/test_filter.cpp
+++ b/test/test_filter.cpp
@@ -444,14 +444,14 @@ TEST(FilterProcessorInplace, translate_esc_single)
     EXPECT_EQ(t.subject, "\t\b\n\r\tn\\r\\t");
     EXPECT_FALSE(t.proc.unfiltered_chars);
     // can write this one
-    t.proc.translate_esc('+');
-    EXPECT_EQ(t.proc.rpos, 12); // this is fine, no read is done
+    t.proc.set('+');
+    EXPECT_EQ(t.proc.rpos, 10); // this is fine, no read is done
     EXPECT_EQ(t.proc.wpos, 10);
     EXPECT_EQ(t.subject, "\t\b\n\r\tn\\r\\+");
     EXPECT_FALSE(t.proc.unfiltered_chars);
     // but this one will set to unfiltered
-    t.proc.translate_esc('x');
-    EXPECT_EQ(t.proc.rpos, 14); // this is fine, no read is done
+    t.proc.set('x');
+    EXPECT_EQ(t.proc.rpos, 10); // this is fine, no read is done
     EXPECT_EQ(t.proc.wpos, 11);
     EXPECT_EQ(t.subject, "\t\b\n\r\tn\\r\\+");
     EXPECT_TRUE(t.proc.unfiltered_chars);
@@ -870,11 +870,11 @@ TEST(FilterProcessorInplace, translate_esc_with_temporary_excess_requirement__tr
     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.sofar(), "0011223");
     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.subject, "00112233445566");
     EXPECT_EQ(t.proc.maxcap, 16);
     EXPECT_TRUE(t.proc.unfiltered_chars);
     // 00112233445566
@@ -884,11 +884,11 @@ TEST(FilterProcessorInplace, translate_esc_with_temporary_excess_requirement__tr
     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.sofar(), "00112233"); // 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.subject, "00112233445566");
     EXPECT_EQ(t.proc.maxcap, 16);
     EXPECT_TRUE(t.proc.unfiltered_chars);
     // 00112233445566
@@ -898,11 +898,11 @@ TEST(FilterProcessorInplace, translate_esc_with_temporary_excess_requirement__tr
     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.sofar(), "001122334"); // 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.subject, "00112233445566");
     EXPECT_EQ(t.proc.maxcap, 16);
     EXPECT_TRUE(t.proc.unfiltered_chars);
     // 00112233445566
@@ -912,11 +912,11 @@ TEST(FilterProcessorInplace, translate_esc_with_temporary_excess_requirement__tr
     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.sofar(), "0011223344"); // 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.subject, "00112233445566");
     EXPECT_EQ(t.proc.maxcap, 16);
     EXPECT_TRUE(t.proc.unfiltered_chars);
     // 00112233445566
@@ -926,11 +926,11 @@ TEST(FilterProcessorInplace, translate_esc_with_temporary_excess_requirement__tr
     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.sofar(), "00112233445");
     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.subject, "00112233445566");
     EXPECT_EQ(t.proc.maxcap, 16);
     EXPECT_TRUE(t.proc.unfiltered_chars);
     // 00112233445566
@@ -940,11 +940,11 @@ TEST(FilterProcessorInplace, translate_esc_with_temporary_excess_requirement__tr
     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.sofar(), "001122334455");
     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.subject, "00112233445566");
     EXPECT_EQ(t.proc.maxcap, 16);
     EXPECT_TRUE(t.proc.unfiltered_chars);
     // 00112233445566
@@ -954,11 +954,11 @@ TEST(FilterProcessorInplace, translate_esc_with_temporary_excess_requirement__tr
     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.sofar(), "0011223344556");
     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.subject, "00112233445566");
     EXPECT_EQ(t.proc.maxcap, 16);
     EXPECT_TRUE(t.proc.unfiltered_chars);
     // 00112233445566
@@ -968,11 +968,11 @@ TEST(FilterProcessorInplace, translate_esc_with_temporary_excess_requirement__tr
     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.sofar(), "00112233445566");
     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.subject, "00112233445566");
     EXPECT_EQ(t.proc.maxcap, 16);
     EXPECT_TRUE(t.proc.unfiltered_chars);
     // 00112233445566
@@ -982,11 +982,11 @@ TEST(FilterProcessorInplace, translate_esc_with_temporary_excess_requirement__tr
     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.sofar(), "00112233445566");
     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.subject, "00112233445566");
     EXPECT_EQ(t.proc.maxcap, 16);
     EXPECT_TRUE(t.proc.unfiltered_chars);
     // 00112233445566
@@ -996,11 +996,11 @@ TEST(FilterProcessorInplace, translate_esc_with_temporary_excess_requirement__tr
     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.sofar(), "00112233445566");
     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.subject, "00112233445566");
     EXPECT_EQ(t.proc.maxcap, 16);
     EXPECT_TRUE(t.proc.unfiltered_chars);
     // 00112233445566
@@ -1010,11 +1010,11 @@ TEST(FilterProcessorInplace, translate_esc_with_temporary_excess_requirement__tr
     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.sofar(), "00112233445566");
     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.subject, "00112233445566");
     EXPECT_EQ(t.proc.maxcap, 17);
     EXPECT_TRUE(t.proc.unfiltered_chars);
 }