--- afdko/c/addfeatures/hotconv/GPOS.cpp
+++ afdko/c/addfeatures/hotconv/GPOS.cpp
@@ -1025,12 +1025,14 @@ GPOS::PairPos::Format1::Format1(GPOS &h, GPOS::SubtableInfo &si) : PairPos(h, si
     auto previ = si.pairs.begin();
     std::vector<decltype(previ)> pairSetEnds;
     cac->coverageBegin();
-    for (auto i = previ + 1; i <= si.pairs.end(); i++) {
+    for (auto i = previ + 1;; i++) {
         if (i == si.pairs.end() || i->first != previ->first) {
             cac->coverageAddGlyph(previ->first);
             pairSetEnds.emplace_back(i);
             previ = i;
         }
+        if (i == si.pairs.end())
+            break;
     }
 
     auto nvals = MetricsInfo::numValues(ValueFormat1) + MetricsInfo::numValues(ValueFormat2);
--- afdko/c/addfeatures/hotconv/otl.cpp
+++ afdko/c/addfeatures/hotconv/otl.cpp
@@ -463,34 +463,41 @@ void OTL::calcFeatureListIndices() {
 void OTL::prepScriptList() {
     std::stable_sort(subtables.begin(), subtables.end(), Subtable::ltScriptList);
 
+    if (subtables.size() == 0)
+        return;
+
     auto prevs = subtables.begin();
-    for (auto ss = prevs + 1; ss <= subtables.end(); ss++) {
+    for (auto ss = prevs + 1;; ss++) {
         if (ss == subtables.end() || (*ss)->isAnon() || (*ss)->isStandAlone() ||
             (*ss)->script != (*prevs)->script) {
             // script change
             (*prevs)->span.script = ss;
 
             auto prevl = prevs;
-            for (auto sl = prevl + 1; sl <= ss ; sl++) {
+            for (auto sl = prevl + 1;; sl++) {
                 if (sl == ss || (*sl)->language != (*prevl)->language) {
                     // language change
                     (*prevl)->span.language = sl;
 
                     auto prevf = prevl;
-                    for (auto sf = prevf + 1; sf <= sl ; sf++) {
+                    for (auto sf = prevf + 1;; sf++) {
                         if (sf == sl ||
                             (*sf)->index.feature != (*prevf)->index.feature) {
                             // feature index change
                             (*prevf)->span.feature = sf;
                             prevf = sf;
                         }
+                        if (sf == sl)
+                            break;
                     }
                     prevl = sl;
                 }
+                if (sl == ss)
+                    break;
             }
             prevs = ss;
         }
-        if (ss != subtables.end() && ((*ss)->isAnon() || (*ss)->isStandAlone()))
+        if (ss == subtables.end() || (*ss)->isAnon() || (*ss)->isStandAlone())
             break;
     }
 }
@@ -560,8 +567,11 @@ Offset OTL::fillScriptList() {
 void OTL::prepFeatureList() {
     std::stable_sort(subtables.begin(), subtables.end(), Subtable::ltFeatureList);
 
+    if (subtables.size() == 0)
+        return;
+
     auto prevf = subtables.begin();
-    for (auto sf = prevf + 1; sf <= subtables.end(); sf++) {
+    for (auto sf = prevf + 1;; sf++) {
         // Whenever we encounter new feature index, store the current subtable
         // index in the first subtable of the sequence of subtables that
         // had the previous subtable index. The array is this divided into
@@ -576,16 +586,18 @@ void OTL::prepFeatureList() {
             (*prevf)->span.feature = sf;
 
             auto prevl = prevf;
-            for (auto sl = prevl + 1; sl <= sf; sl++) {
+            for (auto sl = prevl + 1;; sl++) {
                 if (sl == sf || (*sl)->index.lookup != (*prevl)->index.lookup) {
                     // lookup index change
                     (*prevl)->span.lookup = sl;
                     prevl = sl;
                 }
+                if (sl == sf)
+                    break;
             }
             prevf = sf;
         }
-        if (sf != subtables.end() && ((*sf)->isStandAlone() || (*sf)->isAnon()))
+        if (sf == subtables.end() || (*sf)->isStandAlone() || (*sf)->isAnon())
             break;
     }
 }
@@ -672,8 +684,11 @@ void OTL::fixFeatureParamOffsets(Offset shortfeatureParamBaseOffset) {
 void OTL::prepLookupList() {
     std::stable_sort(subtables.begin(), subtables.end(), Subtable::ltLookupList);
 
+    if (subtables.size() == 0)
+        return;
+
     auto prevl = subtables.begin();
-    for (auto sl = prevl + 1; sl <= subtables.end(); sl++) {
+    for (auto sl = prevl + 1;; sl++) {
         Subtable *slr = sl == subtables.end() ? nullptr : sl->get();
         auto &prevlr = *prevl;
         if (slr == nullptr || slr->isRef() || slr->isParam() ||
@@ -682,7 +697,7 @@ void OTL::prepLookupList() {
             prevlr->span.lookup = sl;
             prevl = sl;
         }
-        if (slr != nullptr && (slr->isRef() || slr->isParam()))
+        if (slr == nullptr || slr->isRef() || slr->isParam())
             break;
     }
 }