diff --git a/python/python-psi-impl/src/com/jetbrains/python/PyNewStyleStringFormatParser.java b/python/python-psi-impl/src/com/jetbrains/python/PyNewStyleStringFormatParser.java
index a7816e0d23cf..8aec13d60adb 100644
--- a/python/python-psi-impl/src/com/jetbrains/python/PyNewStyleStringFormatParser.java
+++ b/python/python-psi-impl/src/com/jetbrains/python/PyNewStyleStringFormatParser.java
@@ -186,7 +186,8 @@ public final class PyNewStyleStringFormatParser {
           formatSpecStart = offset;
         }
       }
-      else if (formatSpecStart >= 0) {
+      else {
+        assert formatSpecStart >= 0;
         if (c == '{') {
           final Field field = parseField(offset, recursionDepth + 1);
           nestedFields.add(field);