diff --git a/python/ql/lib/semmle/python/regex.qll b/python/ql/lib/semmle/python/regex.qll
index ef7c12ac6a5..fd18cd49276 100644
--- a/python/ql/lib/semmle/python/regex.qll
+++ b/python/ql/lib/semmle/python/regex.qll
@@ -204,8 +204,7 @@ abstract class RegexString extends Expr {
     |
       end = inner_end + 1 and
       inner_end > inner_start and
-      this.nonEscapedCharAt(inner_end) = "]" and
-      not exists(int mid | this.nonEscapedCharAt(mid) = "]" | mid > inner_start and mid < inner_end)
+      inner_end = min(int i | this.nonEscapedCharAt(i) = "]" and inner_start < i)
     )
   }
 
@@ -344,9 +343,8 @@ abstract class RegexString extends Expr {
     this.escapingChar(start) and
     this.getChar(start + 1) = "N" and
     this.getChar(start + 2) = "{" and
-    this.getChar(end - 1) = "}" and
     end > start and
-    not exists(int i | start + 2 < i and i < end - 1 | this.getChar(i) = "}")
+    end - 1 = min(int i | start + 2 < i and this.getChar(i) = "}")
   }
 
   /**