diff --git a/components/fpspreadsheet/source/common/fpspreadsheet.pas b/components/fpspreadsheet/source/common/fpspreadsheet.pas
index fc3276fd9..809cd0401 100644
--- a/components/fpspreadsheet/source/common/fpspreadsheet.pas
+++ b/components/fpspreadsheet/source/common/fpspreadsheet.pas
@@ -4950,6 +4950,11 @@ end;
 -------------------------------------------------------------------------------}
 procedure TsWorksheet.WriteCellValueAsString(ACell: PCell; AValue: String;
   const AFormatSettings: TFormatSettings);
+const          // isAMPM   isLongTime
+  TIME_FMT: array[boolean, boolean] of TsNumberFormat = (
+    (nfShortTime, nfLongTime),
+    (nfShortTimeAM, nfLongTimeAM)
+  );
 var
   isPercent: Boolean;
   number: Double;
@@ -4958,9 +4963,12 @@ var
   numFmtParams: TsNumFormatParams;
   maxDig: Integer;
   isMixed: Boolean;
+  isAMPM: Boolean;
+  isLongTime: Boolean;
   rtParams: TsRichTextParams;
   plain: String;
   fmtIndex: Integer;
+  ucValue: String;
 begin
   if ACell = nil then
     exit;
@@ -5047,15 +5055,17 @@ begin
     begin
       if not IsTimeFormat(numFmtParams) then
       begin
-        if IsLongTimeFormat(AValue, AFormatSettings.TimeSeparator) then
-          WriteDateTime(ACell, number, nfLongTime)
-        else
-          WriteDateTime(ACell, number, nfShortTime);
+        ucValue := Uppercase(AValue);
+        isAMPM := (pos('AM', ucValue) > 0) or (pos('PM', ucValue) > 0);
+        isLongTime := IsLongTimeFormat(AValue, AFormatSettings.TimeSeparator);
+        WriteDateTime(ACell, number, TIME_FMT[isAMPM, isLongTime]);
       end;
     end else
     if frac(number) = 0.0 then  // this is a date alone
     begin
-  //    if not IsDateFormat(numFmtParams) then
+      if pos(' ', AValue) > 0 then
+        WriteDateTime(ACell, number, nfShortDateTime)
+      else
         WriteDateTime(ACell, number, nfShortDate);
     end else
     if not IsDateTimeFormat(fmt.NumberFormat) then
diff --git a/components/fpspreadsheet/tests/formattests.pas b/components/fpspreadsheet/tests/formattests.pas
index 7ce1fdde9..29223ff36 100644
--- a/components/fpspreadsheet/tests/formattests.pas
+++ b/components/fpspreadsheet/tests/formattests.pas
@@ -507,8 +507,14 @@ begin
       begin
         if (AFormat = sfExcel2) and (SollDateTimeFormats[Col] in [nfCustom, nfTimeInterval]) then
           Continue;  // The formats nfFmtDateTime and nfTimeInterval are not supported by BIFF2
-        if (AFormat = sfCSV) and (SollDateTimeFormats[Col] in [nfCustom, nfTimeInterval]) then
-          Continue;  // No chance for csv to detect custom formats without further information                                 ActualString := MyWorksheet.ReadAsUTF8Text(Row,Col);
+        if (AFormat = sfCSV) then begin
+          if (SollDateTimeFormats[Col] in [nfCustom, nfTimeInterval]) then
+            Continue;  // No chance for csv to detect custom formats without further information                                 ActualString := MyWorksheet.ReadAsUTF8Text(Row,Col);
+          if (SollDateTimeFormats[Col] in [nfShortDate, nfLongDate, nfShortDateTime])
+             and (SollDateTimes[Row] < 1)
+          then
+            Continue;  // No chance for csv to detect a datetime format < 1 (must be time only)
+        end;
         ActualString := MyWorksheet.ReadAsUTF8Text(Row,Col);
         CheckEquals(
           Lowercase(SollDateTimeStrings[Row, Col]),