diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryResolvedEvent.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryResolvedEvent.java
index 60589f6..72926ee 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryResolvedEvent.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryResolvedEvent.java
@@ -132,14 +132,14 @@
                   + rule.getName()
                   + "' indicated that a canonical reproducible form can be obtained by"
                   + " modifying arguments "
-                  + Printer.getPrinter().repr(diff.getFirst());
+                  + representModifications(diff.getFirst());
         } else {
           this.message =
               "Rule '"
                   + rule.getName()
                   + "' indicated that a canonical reproducible form can be obtained by"
                   + " modifying arguments "
-                  + Printer.getPrinter().repr(diff.getFirst())
+                  + representModifications(diff.getFirst())
                   + " and dropping "
                   + Printer.getPrinter().repr(diff.getSecond());
         }
@@ -216,4 +216,20 @@
     }
     return Pair.of(valuesChanged.build(), keysDropped.build());
   }
+
+  static String representModifications(Map<String, Object> changes) {
+    StringBuilder representation = new StringBuilder();
+    boolean isFirst = true;
+    for (Map.Entry<String, Object> entry : changes.entrySet()) {
+      if (!isFirst) {
+        representation.append(", ");
+      }
+      representation
+          .append(entry.getKey())
+          .append(" = ")
+          .append(Printer.getPrinter().repr(entry.getValue()));
+      isFirst = false;
+    }
+    return representation.toString();
+  }
 }
diff --git a/src/test/java/com/google/devtools/build/lib/bazel/repository/RepositoryResolvedEventTest.java b/src/test/java/com/google/devtools/build/lib/bazel/repository/RepositoryResolvedEventTest.java
index 7444e53..c5cb6bc 100644
--- a/src/test/java/com/google/devtools/build/lib/bazel/repository/RepositoryResolvedEventTest.java
+++ b/src/test/java/com/google/devtools/build/lib/bazel/repository/RepositoryResolvedEventTest.java
@@ -16,6 +16,7 @@
 
 import static com.google.common.truth.Truth.assertThat;
 
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.util.Pair;
 import java.util.List;
@@ -80,4 +81,20 @@
     assertThat(result.getFirst()).containsExactly("foo", "new", "bar", "otherValue");
     assertThat(result.getSecond()).isEmpty();
   }
+
+  @Test
+  public void testRepresentModifications() {
+    assertThat(
+            RepositoryResolvedEvent.representModifications(
+                ImmutableMap.<String, Object>of("a", "b", "c", "d")))
+        .isEqualTo("a = \"b\", c = \"d\"");
+    assertThat(
+            RepositoryResolvedEvent.representModifications(
+                ImmutableMap.<String, Object>of("a", 1, "b", 2)))
+        .isEqualTo("a = 1, b = 2");
+    assertThat(
+            RepositoryResolvedEvent.representModifications(
+                ImmutableMap.<String, Object>of("a", ImmutableList.<Integer>of(1, 2, 3))))
+        .isEqualTo("a = [1, 2, 3]");
+  }
 }