diff --git a/flang/runtime/io-stmt.cpp b/flang/runtime/io-stmt.cpp
--- a/flang/runtime/io-stmt.cpp
+++ b/flang/runtime/io-stmt.cpp
@@ -264,7 +264,16 @@
 ExternalIoStatementState<DIR>::ExternalIoStatementState(
     ExternalFileUnit &unit, const char *sourceFile, int sourceLine)
     : ExternalIoStatementBase{unit, sourceFile, sourceLine}, mutableModes_{
-                                                                 unit.modes} {}
+                                                                 unit.modes} {
+  if constexpr (DIR == Direction::Output) {
+    // If the last statement was a non advancing IO input statement, the unit
+    // furthestPositionInRecord was not advanced, but the positionInRecord may
+    // have been advanced. Advance furthestPositionInRecord here to avoid
+    // overwriting the part of the record that has been read with blanks.
+    unit.furthestPositionInRecord =
+        std::max(unit.furthestPositionInRecord, unit.positionInRecord);
+  }
+}
 
 template <Direction DIR> int ExternalIoStatementState<DIR>::EndIoStatement() {
   if constexpr (DIR == Direction::Input) {
diff --git a/flang/runtime/unit.cpp b/flang/runtime/unit.cpp
--- a/flang/runtime/unit.cpp
+++ b/flang/runtime/unit.cpp
@@ -261,9 +261,10 @@
   if (recordLength) {
     // It is possible for recordLength to have a value now for a
     // variable-length output record if the previous operation
-    // was a BACKSPACE.
+    // was a BACKSPACE or non advancing input statement.
     if (!isFixedRecordLength) {
       recordLength.reset();
+      beganReadingRecord_ = false;
     } else if (furthestAfter > *recordLength) {
       handler.SignalError(IostatRecordWriteOverrun,
           "Attempt to write %zd bytes to position %jd in a fixed-size record "
diff --git a/flang/unittests/Runtime/ExternalIOTest.cpp b/flang/unittests/Runtime/ExternalIOTest.cpp
--- a/flang/unittests/Runtime/ExternalIOTest.cpp
+++ b/flang/unittests/Runtime/ExternalIOTest.cpp
@@ -537,3 +537,98 @@
     j++;
   }
 }
+
+TEST(ExternalIOTests, TestWriteAfterNonAvancingInput) {
+  // OPEN(NEWUNIT=unit,ACCESS='SEQUENTIAL',ACTION='READWRITE',&
+  //   FORM='FORMATTED',STATUS='SCRATCH')
+  auto *io{IONAME(BeginOpenNewUnit)(__FILE__, __LINE__)};
+  ASSERT_TRUE(IONAME(SetAccess)(io, "SEQUENTIAL", 10))
+      << "SetAccess(SEQUENTIAL)";
+  ASSERT_TRUE(IONAME(SetAction)(io, "READWRITE", 9)) << "SetAction(READWRITE)";
+  ASSERT_TRUE(IONAME(SetForm)(io, "FORMATTED", 9)) << "SetForm(FORMATTED)";
+  ASSERT_TRUE(IONAME(SetStatus)(io, "SCRATCH", 7)) << "SetStatus(SCRATCH)";
+
+  int unit{-1};
+  ASSERT_TRUE(IONAME(GetNewUnit)(io, unit)) << "GetNewUnit()";
+  ASSERT_EQ(IONAME(EndIoStatement)(io), IostatOk)
+      << "EndIoStatement() for OpenNewUnit";
+
+  // Write the file to be used for the input test.
+  static constexpr std::string_view records[] = {"ABCDEFGHIJKLMNOPQRST"};
+  static constexpr std::string_view fmt{"(A)"};
+  for (const auto &record : records) {
+    // WRITE(UNIT=unit,FMT=fmt) record
+    io = IONAME(BeginExternalFormattedOutput)(
+        fmt.data(), fmt.length(), unit, __FILE__, __LINE__);
+    ASSERT_TRUE(IONAME(OutputAscii)(io, record.data(), record.length()))
+        << "OutputAscii()";
+    ASSERT_EQ(IONAME(EndIoStatement)(io), IostatOk)
+        << "EndIoStatement() for OutputAscii";
+  }
+
+  // REWIND(UNIT=unit)
+  io = IONAME(BeginRewind)(unit, __FILE__, __LINE__);
+  ASSERT_EQ(IONAME(EndIoStatement)(io), IostatOk)
+      << "EndIoStatement() for Rewind";
+
+  struct TestItems {
+    std::string item;
+    int expectedIoStat;
+    std::string expectedItemValue;
+  };
+  // Actual non advancing input IO test
+  TestItems inputItems[]{
+      {std::string(4, '+'), IostatOk, "ABCD"},
+      {std::string(4, '+'), IostatOk, "EFGH"},
+  };
+
+  int j{0};
+  for (auto &inputItem : inputItems) {
+    // READ(UNIT=unit, FMT=fmt, ADVANCE='NO', IOSTAT=iostat) inputItem
+    io = IONAME(BeginExternalFormattedInput)(
+        fmt.data(), fmt.length(), unit, __FILE__, __LINE__);
+    IONAME(EnableHandlers)(io, true, false, false, false, false);
+    ASSERT_TRUE(IONAME(SetAdvance)(io, "NO", 2)) << "SetAdvance(NO)" << j;
+    ASSERT_TRUE(
+        IONAME(InputAscii)(io, inputItem.item.data(), inputItem.item.length()))
+        << "InputAscii() " << j;
+    ASSERT_EQ(IONAME(EndIoStatement)(io), inputItem.expectedIoStat)
+        << "EndIoStatement() for Read " << j;
+    ASSERT_EQ(inputItem.item, inputItem.expectedItemValue)
+        << "Input-item value after non advancing read " << j;
+    j++;
+  }
+
+  // WRITE(UNIT=unit, FMT=fmt, IOSTAT=iostat) outputItem.
+  static constexpr std::string_view outputItem{"XYZ"};
+  // WRITE(UNIT=unit,FMT=fmt) record
+  io = IONAME(BeginExternalFormattedOutput)(
+      fmt.data(), fmt.length(), unit, __FILE__, __LINE__);
+  ASSERT_TRUE(IONAME(OutputAscii)(io, outputItem.data(), outputItem.length()))
+      << "OutputAscii()";
+  ASSERT_EQ(IONAME(EndIoStatement)(io), IostatOk)
+      << "EndIoStatement() for OutputAscii";
+
+  // Verify that the output was written in the record read in non avdancing
+  // mode, after the read part, and that the end was truncated.
+
+  // REWIND(UNIT=unit)
+  io = IONAME(BeginRewind)(unit, __FILE__, __LINE__);
+  ASSERT_EQ(IONAME(EndIoStatement)(io), IostatOk)
+      << "EndIoStatement() for Rewind";
+
+  std::string resultRecord(20, '+');
+  std::string expectedRecord{"ABCDEFGHXYZ         "};
+  // READ(UNIT=unit, FMT=fmt, IOSTAT=iostat) result
+  io = IONAME(BeginExternalFormattedInput)(
+      fmt.data(), fmt.length(), unit, __FILE__, __LINE__);
+  IONAME(EnableHandlers)(io, true, false, false, false, false);
+  ASSERT_TRUE(
+      IONAME(InputAscii)(io, resultRecord.data(), resultRecord.length()))
+      << "InputAscii() ";
+  ASSERT_EQ(IONAME(EndIoStatement)(io), IostatOk)
+      << "EndIoStatement() for Read ";
+
+  ASSERT_EQ(resultRecord, expectedRecord)
+      << "Record after non advancing read followed by wrote";
+}