diff --git a/src/gui/findReplace.cpp b/src/gui/findReplace.cpp
index 7a7492317..157de0441 100644
--- a/src/gui/findReplace.cpp
+++ b/src/gui/findReplace.cpp
@@ -371,7 +371,7 @@ void FurnaceGUI::doReplace() {
 
     switch (queryReplaceEffectPos) {
       case 0: // clear
-        for (int j=0; j<e->song.subsong[i.subsong]->pat[i.x].effectCols; j++) {
+        for (int j=0; j<e->song.subsong[i.subsong]->pat[i.x].effectCols && j<8; j++) {
           effectOrder[j]=j;
         }
         break;
@@ -380,7 +380,7 @@ void FurnaceGUI::doReplace() {
         for (int j=0; j<8 && placementIndex<8 && i.effectPos[j]>=0; j++) {
           effectOrder[placementIndex++]=i.effectPos[j];
         }
-        for (int j=0; j<e->song.subsong[i.subsong]->pat[i.x].effectCols; j++) {
+        for (int j=0; j<e->song.subsong[i.subsong]->pat[i.x].effectCols && placementIndex<8 && j<8; j++) {
           if (p->data[i.y][4+j*2]!=-1 || p->data[i.y][5+j*2]!=-1) {
             effectOrder[placementIndex++]=j;
           }
@@ -392,7 +392,7 @@ void FurnaceGUI::doReplace() {
         for (int j=0; j<8 && placementIndex<8 && i.effectPos[j]>=0; j++) {
           effectOrder[placementIndex++]=i.effectPos[j];
         }
-        for (int j=0; j<e->song.subsong[i.subsong]->pat[i.x].effectCols; j++) {
+        for (int j=0; j<e->song.subsong[i.subsong]->pat[i.x].effectCols && placementIndex<8 && j<8; j++) {
           if (p->data[i.y][4+j*2]!=-1 || p->data[i.y][5+j*2]!=-1) {
             effectOrder[placementIndex++]=j;
           }
@@ -406,7 +406,7 @@ void FurnaceGUI::doReplace() {
       }
       case 3: { // insert in free spaces
         int placementIndex=0;
-        for (int j=0; j<e->song.subsong[i.subsong]->pat[i.x].effectCols; j++) {
+        for (int j=0; j<e->song.subsong[i.subsong]->pat[i.x].effectCols && j<8; j++) {
           if (p->data[i.y][4+j*2]==-1 && p->data[i.y][5+j*2]==-1) {
             effectOrder[placementIndex++]=j;
           }
@@ -415,7 +415,7 @@ void FurnaceGUI::doReplace() {
       }
     }
 
-    for (int j=0; j<queryReplaceEffectCount; j++) {
+    for (int j=0; j<queryReplaceEffectCount && j<8; j++) {
       signed char pos=effectOrder[j];
       if (pos==-1) continue;
       if (queryReplaceEffectDo[j]) {