diff --git a/src/codeGenerator/astProcessor/binaryAsnProcessor.ts b/src/codeGenerator/astProcessor/binaryAsnProcessor.ts
index 566a2d3..0d0d276 100644
--- a/src/codeGenerator/astProcessor/binaryAsnProcessor.ts
+++ b/src/codeGenerator/astProcessor/binaryAsnProcessor.ts
@@ -144,7 +144,9 @@ export default function binaryAsnProcessor (
 
     function assignmentProc () : GENCODE_SOLVED_OBJECT {
         assignmentStartErrorTests()
-        AuxVars.isLeftSideOfAssignment = true
+        if (CurrentNode.Operation.type === 'Assignment') {
+            AuxVars.isLeftSideOfAssignment = true
+        }
         AuxVars.hasVoidArray = false
         const LGenObj = genCode(Program, AuxVars, {
             RemAST: CurrentNode.Left,
diff --git a/src/codeGenerator/astProcessor/setupGenCode.ts b/src/codeGenerator/astProcessor/setupGenCode.ts
index dcd02c0..5b8b45f 100644
--- a/src/codeGenerator/astProcessor/setupGenCode.ts
+++ b/src/codeGenerator/astProcessor/setupGenCode.ts
@@ -126,6 +126,9 @@ export default function setupGenCode (
         if (MemFound === undefined) {
             throw new Error(`At line: ${line}. Using variable '${varName}' before declaration.`)
         }
+        if (!MemFound.isSet) {
+            detectAndSetNotInitialized(MemFound, line, varDeclaration !== '')
+        }
         if (varDeclaration !== '') { // we are in declarations sentence
             MemFound.isDeclared = true
             return deepCopy(MemFound)
@@ -144,9 +147,24 @@ export default function setupGenCode (
         if (FoundMemory === undefined) {
             throw new Error(`At line: ${line}. No variable found at address '${addr}'.`)
         }
+        if (!FoundMemory.isSet) {
+            detectAndSetNotInitialized(FoundMemory, line, false)
+        }
         return deepCopy(FoundMemory)
     }
 
+    function detectAndSetNotInitialized (Memory: MEMORY_SLOT, line: number, isInitialization: boolean) {
+        if (AuxVars.isLeftSideOfAssignment || Memory.hexContent) {
+            Memory.isSet = true
+            return
+        }
+        if (isInitialization) {
+            return
+        }
+        AuxVars.warnings.push(`Warning: at line ${line}. Variable '${Memory.name}' is used but not initialized.`)
+        Memory.isSet = true // No more warning for same variable
+    }
+
     function auxvarsGetNewJumpID () : string {
         // This code shall be equal GlobalCodeVars.getNewJumpID()
         AuxVars.jumpId++
diff --git a/src/shaper/memoryProcessor.ts b/src/shaper/memoryProcessor.ts
index 469fe09..cd4f6f4 100644
--- a/src/shaper/memoryProcessor.ts
+++ b/src/shaper/memoryProcessor.ts
@@ -106,6 +106,7 @@ export default function memoryProcessor (
             }
         }
         header.isDeclared = AuxVars.isFunctionArgument
+        header.isSet = AuxVars.isFunctionArgument
         // If is not an array, just send the header
         if (dimensions.length === 0) {
             return [header]
@@ -133,6 +134,7 @@ export default function memoryProcessor (
             Mem2.asmName = `${header.asmName}_${i - 1}`
             Mem2.scope = AuxVars.currentScopeName
             Mem2.declaration = header.ArrayItem.declaration
+            Mem2.isSet = true // No way to track array items for using before initialized
             retArrMem.push(Mem2)
         }
         // create array type definition
@@ -277,6 +279,7 @@ export default function memoryProcessor (
             StructMemHeader.asmName = AuxVars.currentPrefix + phraseCode[startingTokenCounter].value
             StructMemHeader.scope = AuxVars.currentScopeName
             StructMemHeader.isDeclared = AuxVars.isFunctionArgument
+            StructMemHeader.isSet = AuxVars.isFunctionArgument
             return [StructMemHeader]
         }
         // It IS array of structs
@@ -293,6 +296,7 @@ export default function memoryProcessor (
         StructMemHeader.asmName = AuxVars.currentPrefix + phraseCode[startingTokenCounter].value
         StructMemHeader.scope = AuxVars.currentScopeName
         StructMemHeader.isDeclared = AuxVars.isFunctionArgument
+        StructMemHeader.isSet = AuxVars.isFunctionArgument
         StructMemHeader.type = 'array'
         StructMemHeader.typeDefinition = StructMemHeader.asmName
         StructMemHeader.ArrayItem = {
diff --git a/src/shaper/templates.ts b/src/shaper/templates.ts
index 7e95e0c..ff50385 100644
--- a/src/shaper/templates.ts
+++ b/src/shaper/templates.ts
@@ -23,6 +23,7 @@ export function getTypeDefinitionTemplate<T extends 'register'|'long'|'fixed'|'s
         RetObj.MemoryTemplate.declaration = 'long'
         RetObj.MemoryTemplate.size = 1
         RetObj.MemoryTemplate.isDeclared = true
+        RetObj.MemoryTemplate.isSet = true
         break
     case 'long':
     case 'void':
@@ -67,6 +68,7 @@ const longArg : MEMORY_SLOT = {
     type: 'long',
     scope: 'dummy',
     declaration: 'long',
+    isSet: false,
     size: 1,
     isDeclared: true
 }
@@ -78,6 +80,7 @@ const longPtrArg : MEMORY_SLOT = {
     type: 'long',
     scope: 'dummy',
     declaration: 'long_ptr',
+    isSet: false,
     size: 1,
     isDeclared: true
 }
@@ -89,6 +92,7 @@ const fixedArg : MEMORY_SLOT = {
     type: 'fixed',
     scope: 'dummy',
     declaration: 'fixed',
+    isSet: false,
     size: 1,
     isDeclared: true
 }
@@ -98,6 +102,7 @@ export const autoCounterTemplate : MEMORY_SLOT = {
     asmName: '_counterTimestamp',
     declaration: 'long',
     isDeclared: true,
+    isSet: false,
     name: '_counterTimestamp',
     scope: '',
     size: 1,
@@ -139,6 +144,7 @@ export const BuiltInTemplate: SC_FUNCTION[] = [
                 type: 'long',
                 scope: 'memcopy',
                 declaration: 'void_ptr',
+                isSet: false,
                 size: 1,
                 isDeclared: true
             },
@@ -149,6 +155,7 @@ export const BuiltInTemplate: SC_FUNCTION[] = [
                 type: 'long',
                 scope: 'memcopy',
                 declaration: 'void_ptr',
+                isSet: false,
                 size: 1,
                 isDeclared: true
             }
@@ -537,6 +544,7 @@ export function getMemoryTemplate (memType: MEMORY_BASE_TYPES) : MEMORY_SLOT {
         asmName: '',
         isDeclared: false,
         declaration: '',
+        isSet: false,
         address: -1,
         name: '',
         scope: '',
@@ -549,6 +557,7 @@ export const fixedBaseTemplate : MEMORY_SLOT = {
     asmName: 'f100000000',
     declaration: 'fixed',
     isDeclared: false,
+    isSet: true,
     name: 'f100000000',
     hexContent: '0000000005f5e100',
     scope: '',
diff --git a/src/typings/syntaxTypes.ts b/src/typings/syntaxTypes.ts
index 55f2144..66fa25b 100644
--- a/src/typings/syntaxTypes.ts
+++ b/src/typings/syntaxTypes.ts
@@ -62,6 +62,8 @@ export type MEMORY_SLOT = {
     isDeclared: boolean
     /** Variable type during declaration */
     declaration: DECLARATION_TYPES
+    /** Control warning if using variables before setting it. */
+    isSet: boolean
     /** Offset in memory. -1 if this slot is not in memory */
     address: number
     /** Variable name */