diff --git a/lib/jkqtcommon/jkqtpbasicimagetools.h b/lib/jkqtcommon/jkqtpbasicimagetools.h
index 9911d2831c..2125c38aa7 100644
--- a/lib/jkqtcommon/jkqtpbasicimagetools.h
+++ b/lib/jkqtcommon/jkqtpbasicimagetools.h
@@ -28,6 +28,7 @@
 #include <cfloat>
 #include <stdint.h>
 #include <QColor>
+#include <vector>
 #include "jkqtcommon/jkqtcommon_imexport.h"
 #include "jkqtcommon/jkqtpmathtools.h"
 
@@ -654,17 +655,17 @@ inline void JKQTPImagePlot_array2RGBimage(const T* dbl_in, int width, int height
 
 
     const T* dbl=dbl_in;
-    T* dbllog=nullptr;
+    QVector<T> dbllog;
     if (logScale) {
         double logB=log10(logBase);
-        dbllog=static_cast<T*>(malloc(static_cast<size_t>(width)*static_cast<size_t>(height)*sizeof(T)));
+        dbllog.resize(static_cast<size_t>(width)*static_cast<size_t>(height));
         //memcpy(dbl, dbl_in, width*height*sizeof(T));
         for (int i=0; i<width*height; i++) {
             dbllog[i]=log10(dbl_in[i])/logB;
         }
         min=log10(min)/logB;
         max=log10(max)/logB;
-        dbl=dbllog;
+        dbl=dbllog.data();
     }
     double delta=max-min;
 
@@ -865,8 +866,6 @@ inline void JKQTPImagePlot_array2RGBimage(const T* dbl_in, int width, int height
             }
        }
      }
-
-    if (logScale) free(dbllog);
 }
 
 
diff --git a/lib/jkqtcommon/jkqtpmathparser.cpp b/lib/jkqtcommon/jkqtpmathparser.cpp
index 68c725621b..77d0d55fb8 100644
--- a/lib/jkqtcommon/jkqtpmathparser.cpp
+++ b/lib/jkqtcommon/jkqtpmathparser.cpp
@@ -1305,17 +1305,17 @@ JKQTPMathParser::jkmpNode* JKQTPMathParser::primary(bool get){
                  jkmpError(jkqtp_format("')' or ',' expected, but '%s' found", currenttokentostring().c_str()));
             }
 
-                    if ( CurrentToken != RBRACKET ) jkmpError(jkqtp_format("')' expected, but '%s' found", currenttokentostring().c_str()));;
-                    JKQTPMathParser::jkmpNode** p=nullptr;
+            if ( CurrentToken != RBRACKET ) jkmpError(jkqtp_format("')' expected, but '%s' found", currenttokentostring().c_str()));;
+            JKQTPMathParser::jkmpNode** p=nullptr;
             if (num>0) {
                p=static_cast<JKQTPMathParser::jkmpNode**>(malloc(sizeof(JKQTPMathParser::jkmpNode*) * num));
                for (int i=0; i<num; i++) {
                  p[i]=params[i];
                }
             }
-                    res=new jkmpFunctionNode(varname, p, num, this, nullptr);
-                    free(params);
-                    getToken();
+            res=new jkmpFunctionNode(varname, p, num, this, nullptr);
+            free(params);
+            getToken();
 
         } else {
           res=new jkmpVariableNode(varname, this, nullptr);
diff --git a/lib/jkqtplotter/graphs/jkqtpimageoverlays.cpp b/lib/jkqtplotter/graphs/jkqtpimageoverlays.cpp
index ae756bc300..eb4adf47e3 100644
--- a/lib/jkqtplotter/graphs/jkqtpimageoverlays.cpp
+++ b/lib/jkqtplotter/graphs/jkqtpimageoverlays.cpp
@@ -367,15 +367,14 @@ int JKQTPColumnOverlayImageEnhanced::getImageColumn() const
 void JKQTPColumnOverlayImageEnhanced::draw(JKQTPEnhancedPainter &painter) {
     const double* d=parent->getDatastore()->getColumnPointer(imageColumn,0);
     size_t imgSize=parent->getDatastore()->getRows(imageColumn);
-    bool* locData=static_cast<bool*>(malloc(imgSize*sizeof(bool)));
-    this->data=locData;
+    QVector<bool> locData(imgSize,false);
+    this->data=locData.data();
     this->Ny= static_cast<int>(imgSize/this->Nx);
     for (size_t i=0; i<imgSize; i++) {
         locData[i]=(d[i]!=0.0);
     }
     JKQTPOverlayImageEnhanced::draw(painter);
-    free(locData);
-    data=nullptr;
+    this->data=nullptr;
 }
 
 bool JKQTPColumnOverlayImageEnhanced::usesColumn(int c) const
diff --git a/lib/jkqtplotter/jkqtpdatastorage.cpp b/lib/jkqtplotter/jkqtpdatastorage.cpp
index c0fb330610..992e8481ca 100644
--- a/lib/jkqtplotter/jkqtpdatastorage.cpp
+++ b/lib/jkqtplotter/jkqtpdatastorage.cpp
@@ -688,7 +688,7 @@ size_t JKQTPDatastore::copyColumn(size_t old_column, size_t start, size_t stride
 {
     JKQTPColumn old=columns[old_column];
     size_t rows=old.getRows();
-    double* d=static_cast<double*>(malloc(rows*sizeof(double)));
+    QVector<double> d(rows, 0.0);
     double* dd=old.getPointer(0);
     size_t j=0;
     for (size_t i=start; i<rows; i+=stride) {
@@ -696,8 +696,7 @@ size_t JKQTPDatastore::copyColumn(size_t old_column, size_t start, size_t stride
         //qDebug()<<old_column<<name<<": "<<j<<i<<d[j];
         j++;
     }
-    size_t n=addCopiedColumn(d, j, name);
-    free(d);
+    size_t n=addCopiedColumn(d.data(), j, name);
     return n;
 }