diff --git a/src/frontends/qt4/GuiTabular.cpp b/src/frontends/qt4/GuiTabular.cpp
index 34d75ba4a2..0a6bd0e051 100644
--- a/src/frontends/qt4/GuiTabular.cpp
+++ b/src/frontends/qt4/GuiTabular.cpp
@@ -648,6 +648,9 @@ void GuiTabular::updateContents()
 	rotateCellCB->setChecked(tabular_.getRotateCell(cell));
 	rotateTabularCB->setChecked(tabular_.rotate);
 
+	// setting as longtable is not allowed when table is inside a float
+	longTabularCB->setEnabled(funcEnabled(Tabular::SET_LONGTABULAR)); 
+
 	longTabularCB->setChecked(tabular_.is_long_tabular);
 
 	update_borders();
diff --git a/src/insets/InsetTabular.cpp b/src/insets/InsetTabular.cpp
index 4c2bbdbfc2..deae4907c5 100644
--- a/src/insets/InsetTabular.cpp
+++ b/src/insets/InsetTabular.cpp
@@ -3891,6 +3891,12 @@ bool InsetTabular::getStatus(Cursor & cur, FuncRequest const & cmd,
 			break;
 
 		case Tabular::SET_LONGTABULAR:
+			// setting as longtable is not allowed when table is inside a float
+			if (cur.innerInsetOfType(FLOAT_CODE) != 0
+				|| cur.innerInsetOfType(WRAP_CODE) != 0)
+				status.setEnabled(false);
+			else
+				status.setEnabled(true);
 			status.setOnOff(tabular.is_long_tabular);
 			break;
 
diff --git a/status.16x b/status.16x
index 0f8f5f94f7..5c0b5b0ec1 100644
--- a/status.16x
+++ b/status.16x
@@ -66,11 +66,14 @@ What's new
 - Make the modules description in Document > Settings fully translatable
   (bug 6987).
 
-- Fix table line bug when unsetting a multicolumn cell via the table dialog
-  (bug 7000). 
+- Fix table line bug when unsetting a multicolumn cell via the table
+  dialog (bug 7000). 
 
 - Fix the display of table cell alignment in the context menu (bug 7053).
 
+- Don't allow to make tables within in floats longtables as this could
+  lead to LaTeX-errors (bug 6585).
+
 - Correct the Denomination of norsk and nynorsk languages.