diff --git a/src/main/java/org/openrewrite/gitlab/MigrateToRules.java b/src/main/java/org/openrewrite/gitlab/MigrateToRules.java
index 60a0151..671b0ce 100644
--- a/src/main/java/org/openrewrite/gitlab/MigrateToRules.java
+++ b/src/main/java/org/openrewrite/gitlab/MigrateToRules.java
@@ -99,7 +99,8 @@ private static Yaml.Mapping migrateWithOnly(Yaml.Mapping m, Yaml.Mapping.Entry o
         String entryPrefix = onlyEntry.getPrefix();
         String baseIndent = entryPrefix.contains("\n") ?
                 entryPrefix.substring(entryPrefix.lastIndexOf('\n') + 1) : "  ";
-        String seqIndent = baseIndent + "  ";
+        String indentUnit = detectIndentUnit(baseIndent, (Yaml.Sequence) onlyEntry.getValue());
+        String seqIndent = baseIndent + indentUnit;
         String contentIndent = seqIndent + "  ";
 
         StringBuilder sb = new StringBuilder("rules:");
@@ -147,7 +148,8 @@ private static Yaml.Mapping migrateExceptOnly(Yaml.Mapping m, Yaml.Mapping.Entry
         String entryPrefix = exceptEntry.getPrefix();
         String baseIndent = entryPrefix.contains("\n") ?
                 entryPrefix.substring(entryPrefix.lastIndexOf('\n') + 1) : "  ";
-        String seqIndent = baseIndent + "  ";
+        String indentUnit = detectIndentUnit(baseIndent, (Yaml.Sequence) exceptEntry.getValue());
+        String seqIndent = baseIndent + indentUnit;
         String contentIndent = seqIndent + "  ";
 
         StringBuilder sb = new StringBuilder("rules:");
@@ -190,6 +192,21 @@ private static Yaml.Mapping migrateExceptOnly(Yaml.Mapping m, Yaml.Mapping.Entry
                 .orElse(null);
     }
 
+    private static String detectIndentUnit(String baseIndent, Yaml.Sequence seq) {
+        List<Yaml.Sequence.Entry> entries = seq.getEntries();
+        if (entries.isEmpty()) {
+            return "  ";
+        }
+        String childPrefix = entries.get(0).getPrefix();
+        String childIndent = childPrefix.contains("\n") ?
+                childPrefix.substring(childPrefix.lastIndexOf('\n') + 1) : "";
+        int increment = childIndent.length() - baseIndent.length();
+        if (increment <= 0) {
+            return "  ";
+        }
+        return childIndent.substring(baseIndent.length());
+    }
+
     static String refToCondition(String ref) {
         switch (ref) {
             case "branches":
diff --git a/src/test/java/org/openrewrite/gitlab/MigrateToRulesTest.java b/src/test/java/org/openrewrite/gitlab/MigrateToRulesTest.java
index ffcddae..06d823e 100644
--- a/src/test/java/org/openrewrite/gitlab/MigrateToRulesTest.java
+++ b/src/test/java/org/openrewrite/gitlab/MigrateToRulesTest.java
@@ -348,6 +348,80 @@ void multipleJobs() {
         );
     }
 
+    @Test
+    void migrateFourSpaceIndentOnly() {
+        rewriteRun(
+          //language=yaml
+          yaml(
+            """
+              build_job:
+                  script: make build
+                  only:
+                      - main
+                      - tags
+              """,
+            """
+              build_job:
+                  script: make build
+                  rules:
+                      - if: $CI_COMMIT_BRANCH == 'main'
+                      - if: $CI_COMMIT_TAG
+              """,
+            source -> source.path(".gitlab-ci.yml")
+          )
+        );
+    }
+
+    @Test
+    void migrateFourSpaceIndentExcept() {
+        rewriteRun(
+          //language=yaml
+          yaml(
+            """
+              build_job:
+                  script: make build
+                  except:
+                      - tags
+              """,
+            """
+              build_job:
+                  script: make build
+                  rules:
+                      - if: $CI_COMMIT_TAG
+                        when: never
+                      - when: always
+              """,
+            source -> source.path(".gitlab-ci.yml")
+          )
+        );
+    }
+
+    @Test
+    void migrateFourSpaceIndentCombined() {
+        rewriteRun(
+          //language=yaml
+          yaml(
+            """
+              build_job:
+                  script: make build
+                  only:
+                      - branches
+                  except:
+                      - main
+              """,
+            """
+              build_job:
+                  script: make build
+                  rules:
+                      - if: $CI_COMMIT_BRANCH == 'main'
+                        when: never
+                      - if: $CI_COMMIT_BRANCH
+              """,
+            source -> source.path(".gitlab-ci.yml")
+          )
+        );
+    }
+
     @Test
     void noopForNonGitlabCiFiles() {
         rewriteRun(