diff --git a/packages/@tailwindcss-cli/src/commands/build/index.ts b/packages/@tailwindcss-cli/src/commands/build/index.ts
index ca3859b6e..7d007f308 100644
--- a/packages/@tailwindcss-cli/src/commands/build/index.ts
+++ b/packages/@tailwindcss-cli/src/commands/build/index.ts
@@ -196,7 +196,9 @@ export async function handle(args: Result<ReturnType<typeof options>>) {
 
         // Scan changed files only for incremental rebuilds.
         else if (rebuildStrategy === 'incremental') {
-          compiledCss = result.rebuild(scanFiles(changedFiles, IO.Sequential | Parsing.Sequential))
+          let newCandidates = scanFiles(changedFiles, IO.Sequential | Parsing.Sequential)
+
+          compiledCss = result.rebuild(newCandidates)
         }
 
         await write(compiledCss, args)
diff --git a/packages/tailwindcss/src/design-system.ts b/packages/tailwindcss/src/design-system.ts
index fa6390f0a..22277eda3 100644
--- a/packages/tailwindcss/src/design-system.ts
+++ b/packages/tailwindcss/src/design-system.ts
@@ -32,8 +32,8 @@ export type DesignSystem = {
 export function buildDesignSystem(theme: Theme): DesignSystem {
   let utilities = createUtilities(theme)
   let variants = createVariants(theme)
-  let invalidRawCandidates = new Set<string>()
 
+  let invalidRawCandidates = new Set<string>()
   let parsedVariants = new DefaultMap((variant) => parseVariant(variant, designSystem))
   let parsedCandidates = new DefaultMap((candidate) => parseCandidate(candidate, designSystem))
   let compiledAstNodes = new DefaultMap((candidate) => compileAstNodes(candidate, designSystem))
diff --git a/packages/tailwindcss/src/index.ts b/packages/tailwindcss/src/index.ts
index d5205bd52..cb5559a1b 100644
--- a/packages/tailwindcss/src/index.ts
+++ b/packages/tailwindcss/src/index.ts
@@ -187,17 +187,20 @@ export function compile(
 
   return {
     rebuild(newRawCandidates: string[]) {
+      let didChange = false
+
       // Add all new candidates unless we know that they are invalid.
-      let previousSize = allValidCandidates.size
+      let prevSize = allValidCandidates.size
       for (let candidate of newRawCandidates) {
         if (!designSystem.isInvalidCandidate(candidate)) {
           allValidCandidates.add(candidate)
+          didChange ||= allValidCandidates.size !== prevSize
         }
       }
 
       // If no new candidates were added, we can return the original CSS. This
       // currently assumes that we only add new candidates and never remove any.
-      if (previousSize === allValidCandidates.size) {
+      if (!didChange) {
         return compiledCss
       }