diff --git a/ext/gmp/gmp.c b/ext/gmp/gmp.c
index 7ae3de3671d..dddd875dac3 100644
--- a/ext/gmp/gmp.c
+++ b/ext/gmp/gmp.c
@@ -866,7 +866,7 @@ static inline void _gmp_unary_opl(INTERNAL_FUNCTION_PARAMETERS, gmp_unary_opl_t
 static bool gmp_verify_base(zend_long base, uint32_t arg_num)
 {
 	if (base && (base < 2 || base > GMP_MAX_BASE)) {
-		zend_argument_value_error(arg_num, "must be between 2 and %d", GMP_MAX_BASE);
+		zend_argument_value_error(arg_num, "must be 0 or between 2 and %d", GMP_MAX_BASE);
 		return false;
 	}
 
diff --git a/ext/gmp/tests/construct.phpt b/ext/gmp/tests/construct.phpt
index 11c80b3d9ed..1b23bd791ed 100644
--- a/ext/gmp/tests/construct.phpt
+++ b/ext/gmp/tests/construct.phpt
@@ -46,6 +46,6 @@ object(GMP)#1 (1) {
   ["num"]=>
   string(1) "6"
 }
-GMP::__construct(): Argument #2 ($base) must be between 2 and 62
+GMP::__construct(): Argument #2 ($base) must be 0 or between 2 and 62
 GMP::__construct(): Argument #1 ($num) is not an integer string
 GMP::__construct(): Argument #1 ($num) is not an integer string
diff --git a/ext/gmp/tests/gmp_init.phpt b/ext/gmp/tests/gmp_init.phpt
index 6ca421b3e86..4032b54ba47 100644
--- a/ext/gmp/tests/gmp_init.phpt
+++ b/ext/gmp/tests/gmp_init.phpt
@@ -37,7 +37,7 @@ object(GMP)#1 (1) {
   string(8) "98765678"
 }
 string(8) "98765678"
-gmp_init(): Argument #2 ($base) must be between 2 and 62
+gmp_init(): Argument #2 ($base) must be 0 or between 2 and 62
 gmp_init(): Argument #1 ($num) is not an integer string
 gmp_init(): Argument #1 ($num) is not an integer string
 gmp_init(): Argument #1 ($num) is not an integer string