diff --git a/src/components/composer/composer/abstract_composer_store.ts b/src/components/composer/composer/abstract_composer_store.ts
index 2401e3207..267c456b2 100644
--- a/src/components/composer/composer/abstract_composer_store.ts
+++ b/src/components/composer/composer/abstract_composer_store.ts
@@ -1,3 +1,4 @@
+import { isSheetAutocomplete } from "../../../formulas";
 import { composerTokenize, EnrichedToken } from "../../../formulas/composer_tokenizer";
 import { POSTFIX_UNARY_OPERATORS } from "../../../formulas/tokenizer";
 import { functionRegistry } from "../../../functions";
@@ -713,9 +714,11 @@ export abstract class AbstractComposerStore extends SpreadsheetStore {
 
   get autocompleteProvider(): AutoCompleteProvider | undefined {
     const content = this.currentContent;
-    const tokenAtCursor = isFormula(content)
-      ? this.tokenAtCursor
-      : { type: "STRING", value: content };
+    const tokenAtCursor =
+      (isFormula(content) && !this.currentTokens.some((token) => token.type === "UNKNOWN")) ||
+      isSheetAutocomplete(this.tokenAtCursor)
+        ? this.tokenAtCursor
+        : { type: "STRING", value: content };
     if (
       this.editionMode === "inactive" ||
       !tokenAtCursor ||
diff --git a/src/components/composer/composer/composer.ts b/src/components/composer/composer/composer.ts
index 8194a9959..2d899b377 100644
--- a/src/components/composer/composer/composer.ts
+++ b/src/components/composer/composer/composer.ts
@@ -3,6 +3,7 @@ import { NEWLINE, PRIMARY_BUTTON_BG, SCROLLBAR_WIDTH } from "../../../constants"
 import { functionRegistry } from "../../../functions/index";
 import { clip, isFormula, setColorAlpha } from "../../../helpers/index";
 
+import { isSheetAutocomplete } from "../../../formulas";
 import { EnrichedToken } from "../../../formulas/composer_tokenizer";
 import { argTargeting } from "../../../functions/arguments";
 import { Store, useLocalStore, useStore } from "../../../store_engine";
@@ -743,8 +744,14 @@ export class Composer extends Component<CellComposerProps, SpreadsheetChildEnv>
     }
     const token = this.props.composerStore.tokenAtCursor;
 
-    if (isFormula(composerStore.currentContent) && token && token.type !== "SYMBOL") {
-      const tokenContext = token.functionContext;
+    if (
+      (isFormula(composerStore.currentContent) &&
+        token &&
+        token.type !== "SYMBOL" &&
+        !this.props.composerStore.currentTokens.some((t) => t.type === "UNKNOWN")) ||
+      isSheetAutocomplete(this.props.composerStore.tokenAtCursor)
+    ) {
+      const tokenContext = token?.functionContext;
       const parentFunction = tokenContext?.parent.toUpperCase();
       if (
         tokenContext &&
diff --git a/src/formulas/helpers.ts b/src/formulas/helpers.ts
index f3c2f270d..e78774d14 100644
--- a/src/formulas/helpers.ts
+++ b/src/formulas/helpers.ts
@@ -1,4 +1,5 @@
 import { functionRegistry } from "../functions";
+import { EnrichedToken } from "./composer_tokenizer";
 import { AST, ASTFuncall, iterateAstNodes, parseTokens } from "./parser";
 import { Token } from "./tokenizer";
 
@@ -38,3 +39,10 @@ function getFunctionsFromAST(ast: AST, functionNames: string[]) {
       args: node.args,
     }));
 }
+
+export function isSheetAutocomplete(tokenAtCursor: EnrichedToken | undefined): boolean {
+  return (
+    (tokenAtCursor?.type === "SYMBOL" || tokenAtCursor?.type === "UNKNOWN") &&
+    tokenAtCursor?.value.startsWith("'")
+  );
+}
diff --git a/tests/composer/auto_complete/function_auto_complete_store.test.ts b/tests/composer/auto_complete/function_auto_complete_store.test.ts
index 5612d45c1..757b93b80 100644
--- a/tests/composer/auto_complete/function_auto_complete_store.test.ts
+++ b/tests/composer/auto_complete/function_auto_complete_store.test.ts
@@ -15,4 +15,22 @@ describe("Function auto complete", () => {
     autoComplete?.selectProposal(proposals![0].text);
     expect(composer.currentContent).toEqual("=SUM(");
   });
+
+  test("starting with unknown character should stop autocomplete even when adding a valid character", () => {
+    const { store: composer, model } = makeStore(CellComposerStore);
+    setCellContent(model, "A1", "=éSUM");
+    composer.startEdition();
+    const autoComplete = composer.autocompleteProvider;
+    const proposals = autoComplete?.proposals;
+    expect(proposals).toBeUndefined();
+  });
+
+  test("adding an unknown character in the middle of a function should stop autocomplete", () => {
+    const { store: composer, model } = makeStore(CellComposerStore);
+    setCellContent(model, "A1", "=SéSUM");
+    composer.startEdition();
+    const autoComplete = composer.autocompleteProvider;
+    const proposals = autoComplete?.proposals;
+    expect(proposals).toBeUndefined();
+  });
 });