diff --git a/CHANGELOG.md b/CHANGELOG.md
index 728869fea..b924d2d76 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@ All notable changes to this project will be documented in this file.
 ## [Unreleased]
 ### Fixed
 - [#1948] Timeout while deobfuscation did not skip method
+- [#1948] NullPointerException on Simplify expressions on incrementent/decrement
 
 ## [18.3.3] - 2023-01-22
 ### Added
diff --git a/libsrc/ffdec_lib/src/com/jpexs/decompiler/flash/abc/avm2/instructions/InstructionDefinition.java b/libsrc/ffdec_lib/src/com/jpexs/decompiler/flash/abc/avm2/instructions/InstructionDefinition.java
index 15f78b070..cf2f4cd67 100644
--- a/libsrc/ffdec_lib/src/com/jpexs/decompiler/flash/abc/avm2/instructions/InstructionDefinition.java
+++ b/libsrc/ffdec_lib/src/com/jpexs/decompiler/flash/abc/avm2/instructions/InstructionDefinition.java
@@ -548,7 +548,7 @@ public abstract class InstructionDefinition implements Serializable {
             LocalRegAVM2Item valueLocalReg = (LocalRegAVM2Item) value;
             LocalRegAVM2Item nameLocalReg = null;
             if (multiname.name instanceof LocalRegAVM2Item) {
-                nameLocalReg = (LocalRegAVM2Item) multiname.name;;
+                nameLocalReg = (LocalRegAVM2Item) multiname.name;
             }
             if (obj instanceof LocalRegAVM2Item) {
                 LocalRegAVM2Item objLocalReg = (LocalRegAVM2Item) obj;
@@ -669,7 +669,7 @@ public abstract class InstructionDefinition implements Serializable {
 
                         if ((valueLocalReg.regIndex == valueSetLocalReg.regIndex)
                                 && (propertyName.multinameIndex == multinameIndex)
-                                && ((nameLocalReg == null && nameSetLocalReg == null) || (nameLocalReg.regIndex == nameSetLocalReg.regIndex))
+                                && ((nameLocalReg == null && nameSetLocalReg == null) || (nameLocalReg != null && nameSetLocalReg != null && nameLocalReg.regIndex == nameSetLocalReg.regIndex))
                                 && (objLocalReg.regIndex == objSetLocalReg.regIndex)) {
                             if (nameSetLocalReg != null) {
                                 propertyName.name = nameSetLocalReg.value;