diff --git a/Zend/tests/bug63173.phpt b/Zend/tests/bug63173.phpt
new file mode 100644
index 00000000000..36ebf203d25
--- /dev/null
+++ b/Zend/tests/bug63173.phpt
@@ -0,0 +1,12 @@
+--TEST--
+Bug #63173: Crash when invoking invalid array callback
+--FILE--
+<?php
+
+// the important part here are the indexes 1 and 2
+$callback = [1 => 0, 2 => 0];
+$callback();
+
+?>
+--EXPECTF--
+Fatal error: Array callback has to contain indices 0 and 1 in %s on line %d
diff --git a/Zend/zend_vm_def.h b/Zend/zend_vm_def.h
index e0fc1bfc5b8..ab5102f1480 100644
--- a/Zend/zend_vm_def.h
+++ b/Zend/zend_vm_def.h
@@ -2807,6 +2807,10 @@ ZEND_VM_HANDLER(59, ZEND_INIT_FCALL_BY_NAME, ANY, CONST|TMP|VAR|CV)
 			zend_hash_index_find(Z_ARRVAL_P(function_name), 0, (void **) &obj);
 			zend_hash_index_find(Z_ARRVAL_P(function_name), 1, (void **) &method);
 
+			if (!obj || !method) {
+				zend_error_noreturn(E_ERROR, "Array callback has to contain indices 0 and 1");
+			}
+
 			if (Z_TYPE_PP(obj) != IS_STRING && Z_TYPE_PP(obj) != IS_OBJECT) {
 				zend_error_noreturn(E_ERROR, "First array member is not a valid class name or object");
 			}
diff --git a/Zend/zend_vm_execute.h b/Zend/zend_vm_execute.h
index b8dac02cbad..258a85fe7f4 100644
--- a/Zend/zend_vm_execute.h
+++ b/Zend/zend_vm_execute.h
@@ -1458,6 +1458,10 @@ static int ZEND_FASTCALL  ZEND_INIT_FCALL_BY_NAME_SPEC_CONST_HANDLER(ZEND_OPCODE
 			zend_hash_index_find(Z_ARRVAL_P(function_name), 0, (void **) &obj);
 			zend_hash_index_find(Z_ARRVAL_P(function_name), 1, (void **) &method);
 
+			if (!obj || !method) {
+				zend_error_noreturn(E_ERROR, "Array callback has to contain indices 0 and 1");
+			}
+
 			if (Z_TYPE_PP(obj) != IS_STRING && Z_TYPE_PP(obj) != IS_OBJECT) {
 				zend_error_noreturn(E_ERROR, "First array member is not a valid class name or object");
 			}
@@ -1774,6 +1778,10 @@ static int ZEND_FASTCALL  ZEND_INIT_FCALL_BY_NAME_SPEC_TMP_HANDLER(ZEND_OPCODE_H
 			zend_hash_index_find(Z_ARRVAL_P(function_name), 0, (void **) &obj);
 			zend_hash_index_find(Z_ARRVAL_P(function_name), 1, (void **) &method);
 
+			if (!obj || !method) {
+				zend_error_noreturn(E_ERROR, "Array callback has to contain indices 0 and 1");
+			}
+
 			if (Z_TYPE_PP(obj) != IS_STRING && Z_TYPE_PP(obj) != IS_OBJECT) {
 				zend_error_noreturn(E_ERROR, "First array member is not a valid class name or object");
 			}
@@ -1940,6 +1948,10 @@ static int ZEND_FASTCALL  ZEND_INIT_FCALL_BY_NAME_SPEC_VAR_HANDLER(ZEND_OPCODE_H
 			zend_hash_index_find(Z_ARRVAL_P(function_name), 0, (void **) &obj);
 			zend_hash_index_find(Z_ARRVAL_P(function_name), 1, (void **) &method);
 
+			if (!obj || !method) {
+				zend_error_noreturn(E_ERROR, "Array callback has to contain indices 0 and 1");
+			}
+
 			if (Z_TYPE_PP(obj) != IS_STRING && Z_TYPE_PP(obj) != IS_OBJECT) {
 				zend_error_noreturn(E_ERROR, "First array member is not a valid class name or object");
 			}
@@ -2141,6 +2153,10 @@ static int ZEND_FASTCALL  ZEND_INIT_FCALL_BY_NAME_SPEC_CV_HANDLER(ZEND_OPCODE_HA
 			zend_hash_index_find(Z_ARRVAL_P(function_name), 0, (void **) &obj);
 			zend_hash_index_find(Z_ARRVAL_P(function_name), 1, (void **) &method);
 
+			if (!obj || !method) {
+				zend_error_noreturn(E_ERROR, "Array callback has to contain indices 0 and 1");
+			}
+
 			if (Z_TYPE_PP(obj) != IS_STRING && Z_TYPE_PP(obj) != IS_OBJECT) {
 				zend_error_noreturn(E_ERROR, "First array member is not a valid class name or object");
 			}