diff --git a/server/opensharing-server-core/src/main/java/io/opensharing/http/Pagination.java b/server/opensharing-server-core/src/main/java/io/opensharing/http/Pagination.java
index f625c97e..dc6796bb 100644
--- a/server/opensharing-server-core/src/main/java/io/opensharing/http/Pagination.java
+++ b/server/opensharing-server-core/src/main/java/io/opensharing/http/Pagination.java
@@ -35,6 +35,18 @@ public static <E, T> ListResponse<T> page(
     return new ListResponse<>(items, rows.size() > size ? encode(offset + size) : null);
   }
 
+  /** Reads a {@code maxResults} query parameter, which is null when absent. */
+  public static Integer maxResults(String value) {
+    if (value == null || value.isEmpty()) {
+      return null;
+    }
+    try {
+      return Integer.valueOf(value);
+    } catch (NumberFormatException notAnInteger) {
+      throw ApiException.invalidParameter("maxResults must be an integer");
+    }
+  }
+
   private static int pageSize(Integer maxResults) {
     if (maxResults == null || maxResults == 0) {
       return MAX_RESULTS;
diff --git a/server/opensharing-server/src/main/java/io/opensharing/recipient/RecipientAdminService.java b/server/opensharing-server/src/main/java/io/opensharing/recipient/RecipientAdminService.java
index 629d16a2..b0aab8e6 100644
--- a/server/opensharing-server/src/main/java/io/opensharing/recipient/RecipientAdminService.java
+++ b/server/opensharing-server/src/main/java/io/opensharing/recipient/RecipientAdminService.java
@@ -14,6 +14,7 @@
 import com.linecorp.armeria.server.annotation.StatusCode;
 import io.opensharing.auth.ProviderTokenDecorator;
 import io.opensharing.http.ListResponse;
+import io.opensharing.http.Pagination;
 
 /**
  * Provider HTTP API for recipient CRUD, behind {@link ProviderTokenDecorator}. Only the owner may
@@ -53,10 +54,13 @@ public RecipientResponse create(ServiceRequestContext ctx, CreateRecipientReques
   @Get("/recipients")
   public ListResponse<RecipientResponse> list(
       ServiceRequestContext ctx,
-      @Param @Nullable Integer maxResults,
+      @Param @Nullable String maxResults,
       @Param @Nullable String pageToken) {
     return recipients.list(
-        ProviderTokenDecorator.user(ctx), maxResults, pageToken, activationBaseUrl);
+        ProviderTokenDecorator.user(ctx),
+        Pagination.maxResults(maxResults),
+        pageToken,
+        activationBaseUrl);
   }
 
   /**
diff --git a/server/opensharing-server/src/main/java/io/opensharing/share/ShareAdminService.java b/server/opensharing-server/src/main/java/io/opensharing/share/ShareAdminService.java
index 8bf8b78c..c75314ca 100644
--- a/server/opensharing-server/src/main/java/io/opensharing/share/ShareAdminService.java
+++ b/server/opensharing-server/src/main/java/io/opensharing/share/ShareAdminService.java
@@ -15,6 +15,7 @@
 import com.linecorp.armeria.server.annotation.StatusCode;
 import io.opensharing.auth.ProviderTokenDecorator;
 import io.opensharing.http.ListResponse;
+import io.opensharing.http.Pagination;
 
 /**
  * Provider HTTP API for share CRUD and recipient grants, behind {@link ProviderTokenDecorator}.
@@ -45,9 +46,10 @@ public ShareResponse create(ServiceRequestContext ctx, CreateShareRequest reques
   @Get("/shares")
   public ListResponse<ShareResponse> list(
       ServiceRequestContext ctx,
-      @Param @Nullable Integer maxResults,
+      @Param @Nullable String maxResults,
       @Param @Nullable String pageToken) {
-    return shares.list(ProviderTokenDecorator.user(ctx), maxResults, pageToken);
+    return shares.list(
+        ProviderTokenDecorator.user(ctx), Pagination.maxResults(maxResults), pageToken);
   }
 
   /**
@@ -87,9 +89,10 @@ public HttpResponse delete(ServiceRequestContext ctx, @Param String share) {
   public ListResponse<SharePermissionResponse> listPermissions(
       ServiceRequestContext ctx,
       @Param String share,
-      @Param @Nullable Integer maxResults,
+      @Param @Nullable String maxResults,
       @Param @Nullable String pageToken) {
-    return shares.listPermissions(ProviderTokenDecorator.user(ctx), share, maxResults, pageToken);
+    return shares.listPermissions(
+        ProviderTokenDecorator.user(ctx), share, Pagination.maxResults(maxResults), pageToken);
   }
 
   /**
diff --git a/server/opensharing-server/src/test/java/io/opensharing/http/ProviderMaxResultsTest.java b/server/opensharing-server/src/test/java/io/opensharing/http/ProviderMaxResultsTest.java
new file mode 100644
index 00000000..3de3ce54
--- /dev/null
+++ b/server/opensharing-server/src/test/java/io/opensharing/http/ProviderMaxResultsTest.java
@@ -0,0 +1,50 @@
+package io.opensharing.http;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import io.opensharing.TestServer;
+import io.opensharing.TestServer.Response;
+import java.util.List;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+class ProviderMaxResultsTest {
+
+  private static final String SHARES = "/api/1.0/opensharing/provider/shares";
+  private static final String RECIPIENTS = "/api/1.0/opensharing/provider/recipients";
+
+  private static TestServer server;
+
+  @BeforeAll
+  static void startServer() {
+    server = TestServer.start();
+  }
+
+  @AfterAll
+  static void stopServer() {
+    server.close();
+  }
+
+  @Test
+  void rejectsAMaxResultsThatIsNotAnInteger() {
+    assertEquals(201, server.post(SHARES, "alice-token", "{\"name\":\"max-results\"}").status());
+    for (String list : List.of(SHARES, RECIPIENTS, SHARES + "/max-results/permissions")) {
+      for (String value : List.of("ten", "1.5", "3000000000")) {
+        Response invalid = server.get(list + "?maxResults=" + value, "alice-token");
+        assertEquals(400, invalid.status(), list);
+        assertEquals(ErrorCodes.INVALID_PARAMETER_VALUE, invalid.errorCode());
+        assertEquals("maxResults must be an integer", invalid.body().path("message").asText());
+      }
+    }
+  }
+
+  @Test
+  void treatsAnEmptyMaxResultsAsUnset() {
+    for (String list : List.of(SHARES, RECIPIENTS)) {
+      Response unset = server.get(list + "?maxResults=", "alice-token");
+      assertEquals(200, unset.status(), list);
+      assertEquals(server.get(list, "alice-token").body(), unset.body());
+    }
+  }
+}