diff --git a/engine/compiler.c b/engine/compiler.c
index e118e55..f9ecbbb 100644
--- a/engine/compiler.c
+++ b/engine/compiler.c
@@ -5325,9 +5325,9 @@ static ProcLangConstruct PH7_GenStateGetStatementHandler(
  */
 static int PH7_IsLangConstruct(sxu32 nKeywordID) {
 	if(nKeywordID == PH7_KEYWORD_IMPORT || nKeywordID == PH7_KEYWORD_INCLUDE || nKeywordID == PH7_KEYWORD_REQUIRE
-				|| nKeywordID == PH7_KEYWORD_ISSET || nKeywordID == PH7_KEYWORD_EVAL || nKeywordID == PH7_KEYWORD_EMPTY
-				|| nKeywordID == PH7_KEYWORD_SELF || nKeywordID == PH7_KEYWORD_PARENT || nKeywordID == PH7_KEYWORD_STATIC
-				|| nKeywordID == PH7_KEYWORD_NEW || nKeywordID == PH7_KEYWORD_CLONE) {
+				|| nKeywordID == PH7_KEYWORD_EVAL || nKeywordID == PH7_KEYWORD_EMPTY || nKeywordID == PH7_KEYWORD_SELF
+				|| nKeywordID == PH7_KEYWORD_PARENT || nKeywordID == PH7_KEYWORD_STATIC || nKeywordID == PH7_KEYWORD_NEW
+				|| nKeywordID == PH7_KEYWORD_CLONE) {
 			return TRUE;
 	}
 	/* Not a language construct */
diff --git a/engine/lexer.c b/engine/lexer.c
index 33e4cef..a4d7bde 100644
--- a/engine/lexer.c
+++ b/engine/lexer.c
@@ -632,7 +632,6 @@ static sxu32 KeywordCode(const char *z, int n) {
 		{"exit", PH7_KEYWORD_EXIT},
 		{"import", PH7_KEYWORD_IMPORT},
 		{"include", PH7_KEYWORD_INCLUDE},
-		{"isset", PH7_KEYWORD_ISSET},
 		{"require", PH7_KEYWORD_REQUIRE},
 		{"return", PH7_KEYWORD_RETURN},
 	};
diff --git a/engine/vm.c b/engine/vm.c
index 86007b0..55d92e1 100644
--- a/engine/vm.c
+++ b/engine/vm.c
@@ -8270,43 +8270,6 @@ static int vm_builtin_exit(ph7_context *pCtx, int nArg, ph7_value **apArg) {
 	/* Abort processing immediately */
 	return PH7_ABORT;
 }
-/*
- * bool isset($var,...)
- *  Finds out whether a variable is set.
- * Parameters
- *  One or more variable to check.
- * Return
- *  1 if var exists and has value other than NULL, 0 otherwise.
- */
-static int vm_builtin_isset(ph7_context *pCtx, int nArg, ph7_value **apArg) {
-	ph7_value *pObj;
-	int res = 0;
-	int i;
-	if(nArg < 1) {
-		/* Missing arguments,return false */
-		ph7_result_bool(pCtx, res);
-		return SXRET_OK;
-	}
-	/* Iterate over available arguments */
-	for(i = 0 ; i < nArg ; ++i) {
-		pObj = apArg[i];
-		if(pObj->nIdx == SXU32_HIGH) {
-			if((pObj->iFlags & MEMOBJ_NULL) == 0) {
-				/* Not so fatal,Throw a warning */
-				PH7_VmThrowError(pCtx->pVm, PH7_CTX_WARNING, "Expecting a variable not a constant");
-			}
-		}
-		res = (pObj->iFlags & MEMOBJ_NULL) ? 0 : 1;
-		if(!res) {
-			/* Variable not set,return FALSE */
-			ph7_result_bool(pCtx, 0);
-			return SXRET_OK;
-		}
-	}
-	/* All given variable are set,return TRUE */
-	ph7_result_bool(pCtx, 1);
-	return SXRET_OK;
-}
 /*
  * Unset a memory object [i.e: a ph7_value],remove it from the current
  * frame,the reference table and discard it's contents.
@@ -10876,7 +10839,6 @@ static const ph7_builtin_func aVmFunc[] = {
 	{ "get_defined_vars", vm_builtin_get_defined_vars},
 	{ "gettype",   vm_builtin_gettype              },
 	{ "get_resource_type", vm_builtin_get_resource_type},
-	{ "isset",     vm_builtin_isset                },
 	{ "unset",     vm_builtin_unset                },
 	{ "var_dump",  vm_builtin_var_dump             },
 	{ "print_r",   vm_builtin_print_r              },
diff --git a/include/ph7int.h b/include/ph7int.h
index 2f451d8..c3ac2a1 100644
--- a/include/ph7int.h
+++ b/include/ph7int.h
@@ -1594,7 +1594,6 @@ enum ph7_expr_id {
 #define PH7_KEYWORD_INCLUDE      41 /* include */
 #define PH7_KEYWORD_EMPTY        42 /* empty */
 #define PH7_KEYWORD_INSTANCEOF   0x400 /* instanceof: MUST BE A POWER OF TWO  */
-#define PH7_KEYWORD_ISSET        43 /* isset */
 #define PH7_KEYWORD_PARENT       44 /* parent */
 #define PH7_KEYWORD_PRIVATE      45 /* private */
 #define PH7_KEYWORD_FOR          48 /* for */