diff --git a/src/lexer/lexer.cpp b/src/lexer/lexer.cpp
index 4622411..5b568e4 100644
--- a/src/lexer/lexer.cpp
+++ b/src/lexer/lexer.cpp
@@ -68,7 +68,13 @@ const std::vector<Token*> Lexer::makeTokens() {
         } else if (currentChar == ']') {
             tokens.emplace_back(new Token(TokenType::RSQRBRACKET, line, column));
         } else if (currentChar == '=') {
-            tokens.emplace_back(new Token(TokenType::EQUALS, line, column));
+            advance();
+            if (idx >= expr->size() || currentChar != '=') {
+                tokens.emplace_back(new Token(TokenType::EQUALS, line, column));
+                continue;
+            } else {
+                throw PSC::LexerError(line, column - 1, "Invalid token '=='\nIf you want to check for equality, use single '=' instead");
+            }
         } else if (currentChar == ':') {
             tokens.emplace_back(new Token(TokenType::COLON, line, column));
         } else if (currentChar == ',') {
diff --git a/src/nodes/functions/function.cpp b/src/nodes/functions/function.cpp
index 3fb5efe..15ed111 100644
--- a/src/nodes/functions/function.cpp
+++ b/src/nodes/functions/function.cpp
@@ -30,7 +30,7 @@ std::unique_ptr<NodeResult> FunctionNode::evaluate(PSC::Context &ctx) {
 
     PSC::DataType returnDataType = ctx.getType(returnType);
     if (returnDataType == PSC::DataType::NONE)
-        throw PSC::NotDefinedError(returnType, ctx, "Type '" + returnType.value + "'");
+        throw PSC::TypeNotDefinedError(returnType, ctx, returnType.value);
 
     size_t parametersSize = parameterNames.size();
     std::vector<PSC::Parameter> parameters;
@@ -39,7 +39,7 @@ std::unique_ptr<NodeResult> FunctionNode::evaluate(PSC::Context &ctx) {
         const Token *typeToken = parameterTypes[i];
         PSC::DataType type = ctx.getType(*typeToken);
         if (type == PSC::DataType::NONE)
-            throw PSC::NotDefinedError(*typeToken, ctx, "Type '" + typeToken->value + "'");
+            throw PSC::TypeNotDefinedError(*typeToken, ctx, typeToken->value);
         parameters.emplace_back(parameterNames[i], type, parameterPassTypes[i]);
     }
 
diff --git a/src/nodes/functions/procedure.cpp b/src/nodes/functions/procedure.cpp
index f1b4b18..e84dc65 100644
--- a/src/nodes/functions/procedure.cpp
+++ b/src/nodes/functions/procedure.cpp
@@ -33,7 +33,7 @@ std::unique_ptr<NodeResult> ProcedureNode::evaluate(PSC::Context &ctx) {
         const Token *typeToken = parameterTypes[i];
         PSC::DataType type = ctx.getType(*typeToken);
         if (type == PSC::DataType::NONE)
-            throw PSC::NotDefinedError(*typeToken, ctx, "Type '" + typeToken->value + "'");
+            throw PSC::TypeNotDefinedError(*typeToken, ctx, typeToken->value);
         parameters.emplace_back(parameterNames[i], type, parameterPassTypes[i]);
     }
 
diff --git a/src/nodes/variable/array.cpp b/src/nodes/variable/array.cpp
index 51d3c60..8a6cce5 100644
--- a/src/nodes/variable/array.cpp
+++ b/src/nodes/variable/array.cpp
@@ -42,7 +42,7 @@ std::unique_ptr<NodeResult> ArrayDeclareNode::evaluate(PSC::Context &ctx) {
     for (auto identifier : identifiers) {
         PSC::DataType dataType = ctx.getType(type);
         if (dataType.type == PSC::DataType::NONE)
-            throw PSC::NotDefinedError(token, ctx, "Type '" + type.value + "'");
+            throw PSC::TypeNotDefinedError(token, ctx, type.value);
 
         auto array = std::make_unique<PSC::Array>(identifier->value, dataType, dimensions);
         array->init(ctx);
diff --git a/src/nodes/variable/pointer.cpp b/src/nodes/variable/pointer.cpp
index 93e51d6..10a1694 100644
--- a/src/nodes/variable/pointer.cpp
+++ b/src/nodes/variable/pointer.cpp
@@ -10,7 +10,7 @@ PointerDefineNode::PointerDefineNode(const Token &token, const Token &name, cons
 std::unique_ptr<NodeResult> PointerDefineNode::evaluate(PSC::Context &ctx) {
     PSC::DataType pointerType = ctx.getType(type);
     if (pointerType == PSC::DataType::NONE)
-        throw PSC::NotDefinedError(token, ctx, "Type '" + type.value + "'");
+        throw PSC::TypeNotDefinedError(token, ctx, type.value);
 
     if (ctx.isIdentifierType(name, false))
         throw PSC::RedefinitionError(token, ctx, name.value);
diff --git a/src/nodes/variable/variable.cpp b/src/nodes/variable/variable.cpp
index e5f8e58..b287444 100644
--- a/src/nodes/variable/variable.cpp
+++ b/src/nodes/variable/variable.cpp
@@ -19,7 +19,7 @@ std::unique_ptr<NodeResult> DeclareNode::evaluate(PSC::Context &ctx) {
 
         PSC::DataType dataType = ctx.getType(type);
         if (dataType == PSC::DataType::NONE)
-            throw PSC::NotDefinedError(token, ctx, "Type '" + type.value + "'");
+            throw PSC::TypeNotDefinedError(token, ctx, type.value);
 
         ctx.addVariable(new PSC::Variable(identifier->value, dataType, false, &ctx));
     }
diff --git a/src/psc/error.cpp b/src/psc/error.cpp
index ed00127..acdb67d 100644
--- a/src/psc/error.cpp
+++ b/src/psc/error.cpp
@@ -107,8 +107,29 @@ ConstAssignError::ConstAssignError(const Token &token, const Context &context, c
     : RuntimeError(token, context, "Assignment to constant '" + constant + "'")
 {}
 
-NotDefinedError::NotDefinedError(const Token &token, const Context &context, const std::string &identifier)
-    : RuntimeError(token, context, identifier + " is not defined")
+NotDefinedError::NotDefinedError(const Token &token, const Context &context, const std::string &identifier, const std::string &hint)
+    : RuntimeError(token, context, identifier + " is not defined" + hint)
+{}
+
+inline std::string getTypeHint(const std::string &s) {
+    std::string hint = "";
+
+    if (s == "INT")
+        hint = "\nDid you mean 'INTEGER'?";
+    else if (s == "FLOAT")
+        hint = "\nDid you mean 'REAL'?";
+    else if (s == "CHARACTER")
+        hint = "\nDid you mean 'CHAR'?";
+    else if (s == "BOOL")
+        hint = "\nDid you mean 'BOOLEAN'?";
+    else if (s == "STR")
+        hint = "\nDid you mean 'STRING'?";
+
+    return hint;
+}
+
+TypeNotDefinedError::TypeNotDefinedError(const Token &token, const Context &context, const std::string &type)
+    : NotDefinedError(token, context, "Type '" + type + "'", getTypeHint(type))
 {}
 
 ArrayDirectAccessError::ArrayDirectAccessError(const Token &token, const Context &context)
diff --git a/src/psc/error.h b/src/psc/error.h
index 23d3bef..115c821 100644
--- a/src/psc/error.h
+++ b/src/psc/error.h
@@ -97,7 +97,12 @@ namespace PSC {
 
     class NotDefinedError : public RuntimeError {
     public:
-        NotDefinedError(const Token &token, const Context &context, const std::string &identifier);
+        NotDefinedError(const Token &token, const Context &context, const std::string &identifier, const std::string &hint = "");
+    };
+
+    class TypeNotDefinedError : public NotDefinedError {
+    public:
+        TypeNotDefinedError(const Token &token, const Context &context, const std::string &type);
     };
 
     class ArrayDirectAccessError : public RuntimeError {