diff --git a/ext/pdo_firebird/firebird_driver.c b/ext/pdo_firebird/firebird_driver.c
index 9d7cb20d2cdeb..0666057b66b6e 100644
--- a/ext/pdo_firebird/firebird_driver.c
+++ b/ext/pdo_firebird/firebird_driver.c
@@ -599,13 +599,13 @@ static void firebird_handle_closer(pdo_dbh_t *dbh) /* {{{ */
 	}
 
 	if (H->date_format) {
-		efree(H->date_format);
+		zend_string_release_ex(H->date_format, false);
 	}
 	if (H->time_format) {
-		efree(H->time_format);
+		zend_string_release_ex(H->time_format, false);
 	}
 	if (H->timestamp_format) {
-		efree(H->timestamp_format);
+		zend_string_release_ex(H->timestamp_format, false);
 	}
 
 	if (H->einfo.errmsg) {
@@ -1091,10 +1091,9 @@ static bool pdo_firebird_set_attribute(pdo_dbh_t *dbh, zend_long attr, zval *val
 					return false;
 				}
 				if (H->date_format) {
-					efree(H->date_format);
+					zend_string_release_ex(H->date_format, false);
 				}
-				spprintf(&H->date_format, 0, "%s", ZSTR_VAL(str));
-				zend_string_release_ex(str, 0);
+				H->date_format = str;
 			}
 			return true;
 
@@ -1105,10 +1104,9 @@ static bool pdo_firebird_set_attribute(pdo_dbh_t *dbh, zend_long attr, zval *val
 					return false;
 				}
 				if (H->time_format) {
-					efree(H->time_format);
+					zend_string_release_ex(H->time_format, false);
 				}
-				spprintf(&H->time_format, 0, "%s", ZSTR_VAL(str));
-				zend_string_release_ex(str, 0);
+				H->time_format = str;
 			}
 			return true;
 
@@ -1119,10 +1117,9 @@ static bool pdo_firebird_set_attribute(pdo_dbh_t *dbh, zend_long attr, zval *val
 					return false;
 				}
 				if (H->timestamp_format) {
-					efree(H->timestamp_format);
+					zend_string_release_ex(H->timestamp_format, false);
 				}
-				spprintf(&H->timestamp_format, 0, "%s", ZSTR_VAL(str));
-				zend_string_release_ex(str, 0);
+				H->timestamp_format = str;
 			}
 			return true;
 
@@ -1243,15 +1240,27 @@ static int pdo_firebird_get_attribute(pdo_dbh_t *dbh, zend_long attr, zval *val)
 			return 1;
 
 		case PDO_FB_ATTR_DATE_FORMAT:
-			ZVAL_STRING(val, H->date_format ? H->date_format : PDO_FB_DEF_DATE_FMT);
+			if (H->date_format) {
+				ZVAL_STR_COPY(val, H->date_format);
+			} else {
+				ZVAL_STRING(val, PDO_FB_DEF_DATE_FMT);
+			}
 			return 1;
 
 		case PDO_FB_ATTR_TIME_FORMAT:
-			ZVAL_STRING(val, H->time_format ? H->time_format : PDO_FB_DEF_TIME_FMT);
+			if (H->time_format) {
+				ZVAL_STR_COPY(val, H->time_format);
+			} else {
+				ZVAL_STRING(val, PDO_FB_DEF_TIME_FMT);
+			}
 			return 1;
 
 		case PDO_FB_ATTR_TIMESTAMP_FORMAT:
-			ZVAL_STRING(val, H->timestamp_format ? H->timestamp_format : PDO_FB_DEF_TIMESTAMP_FMT);
+			if (H->timestamp_format) {
+				ZVAL_STR_COPY(val, H->timestamp_format);
+			} else {
+				ZVAL_STRING(val, PDO_FB_DEF_TIMESTAMP_FMT);
+			}
 			return 1;
 
 		case PDO_FB_TRANSACTION_ISOLATION_LEVEL:
diff --git a/ext/pdo_firebird/firebird_statement.c b/ext/pdo_firebird/firebird_statement.c
index 60a5e60e11bde..4310269314ce0 100644
--- a/ext/pdo_firebird/firebird_statement.c
+++ b/ext/pdo_firebird/firebird_statement.c
@@ -93,7 +93,7 @@ static int get_formatted_time_tz(pdo_stmt_t *stmt, const ISC_TIME_TZ* timeTz, zv
 	}
 	time = fb_encode_time(hours, minutes, seconds, fractions);
 	isc_decode_sql_time(&time, &t);
-	fmt = S->H->time_format ? S->H->time_format : PDO_FB_DEF_TIME_FMT;
+	fmt = S->H->time_format ? ZSTR_VAL(S->H->time_format) : PDO_FB_DEF_TIME_FMT;
 
 	size_t len = strftime(timeBuf, sizeof(timeBuf), fmt, &t);
 	if (len == 0) {
@@ -123,7 +123,7 @@ static int get_formatted_timestamp_tz(pdo_stmt_t *stmt, const ISC_TIMESTAMP_TZ*
 	ts.timestamp_time = fb_encode_time(hours, minutes, seconds, fractions);
 	isc_decode_timestamp(&ts, &t);
 
-	fmt = S->H->timestamp_format ? S->H->timestamp_format : PDO_FB_DEF_TIMESTAMP_FMT;
+	fmt = S->H->timestamp_format ? ZSTR_VAL(S->H->timestamp_format) : PDO_FB_DEF_TIMESTAMP_FMT;
 
 	size_t len = strftime(timestampBuf, sizeof(timestampBuf), fmt, &t);
 	if (len == 0) {
@@ -546,18 +546,18 @@ static int pdo_firebird_stmt_get_col(
 					break;
 				case SQL_TYPE_DATE:
 					isc_decode_sql_date((ISC_DATE*)var->sqldata, &t);
-					fmt = S->H->date_format ? S->H->date_format : PDO_FB_DEF_DATE_FMT;
+					fmt = S->H->date_format ? ZSTR_VAL(S->H->date_format) : PDO_FB_DEF_DATE_FMT;
 					if (0) {
 				case SQL_TYPE_TIME:
 						isc_decode_sql_time((ISC_TIME*)var->sqldata, &t);
-						fmt = S->H->time_format ? S->H->time_format : PDO_FB_DEF_TIME_FMT;
+						fmt = S->H->time_format ? ZSTR_VAL(S->H->time_format) : PDO_FB_DEF_TIME_FMT;
 					} else if (0) {
 				case SQL_TIMESTAMP:
 						{
 							ISC_TIMESTAMP timestamp = php_get_isc_timestamp_from_sqldata(var->sqldata);
 							isc_decode_timestamp(&timestamp, &t);
 						}
-						fmt = S->H->timestamp_format ? S->H->timestamp_format : PDO_FB_DEF_TIMESTAMP_FMT;
+						fmt = S->H->timestamp_format ? ZSTR_VAL(S->H->timestamp_format) : PDO_FB_DEF_TIMESTAMP_FMT;
 					}
 					/* convert the timestamp into a string */
 					char buf[80];
diff --git a/ext/pdo_firebird/php_pdo_firebird_int.h b/ext/pdo_firebird/php_pdo_firebird_int.h
index a62c152ffab3e..1d58be1c4b717 100644
--- a/ext/pdo_firebird/php_pdo_firebird_int.h
+++ b/ext/pdo_firebird/php_pdo_firebird_int.h
@@ -73,9 +73,9 @@ typedef struct {
 	zend_ulong txn_isolation_level;
 
 	/* date and time format strings, can be set by the set_attribute method */
-	char *date_format;
-	char *time_format;
-	char *timestamp_format;
+	zend_string *date_format;
+	zend_string *time_format;
+	zend_string *timestamp_format;
 
 	unsigned sql_dialect:2;