diff --git a/langchain4j-ollama/src/main/java/dev/langchain4j/model/ollama/OllamaMessagesUtils.java b/langchain4j-ollama/src/main/java/dev/langchain4j/model/ollama/OllamaMessagesUtils.java
index 3ba5e1ea2..abb3670c1 100644
--- a/langchain4j-ollama/src/main/java/dev/langchain4j/model/ollama/OllamaMessagesUtils.java
+++ b/langchain4j-ollama/src/main/java/dev/langchain4j/model/ollama/OllamaMessagesUtils.java
@@ -42,7 +42,7 @@ class OllamaMessagesUtils {
                                 .function(Function.builder()
                                         .name(toolSpecification.name())
                                         .description(toolSpecification.description())
-                                        .parameters(Parameters.builder()
+                                        .parameters(toolSpecification.parameters() == null ? null : Parameters.builder()
                                                 .properties(toolSpecification.parameters().properties())
                                                 .required(toolSpecification.parameters().required())
                                                 .build())
diff --git a/langchain4j-ollama/src/test/java/dev/langchain4j/model/ollama/OllamaToolChatModelIT.java b/langchain4j-ollama/src/test/java/dev/langchain4j/model/ollama/OllamaToolChatModelIT.java
index 5f4c944bb..735bc97d1 100644
--- a/langchain4j-ollama/src/test/java/dev/langchain4j/model/ollama/OllamaToolChatModelIT.java
+++ b/langchain4j-ollama/src/test/java/dev/langchain4j/model/ollama/OllamaToolChatModelIT.java
@@ -20,6 +20,7 @@ import static dev.langchain4j.model.ollama.OllamaImage.TOOL_MODEL;
 import static java.util.Arrays.asList;
 import static java.util.Collections.singletonList;
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 
 class OllamaToolChatModelIT extends AbstractOllamaToolsLanguageModelInfrastructure {
 
@@ -31,6 +32,11 @@ class OllamaToolChatModelIT extends AbstractOllamaToolsLanguageModelInfrastructu
             .addParameter("location", STRING, description("The location to get the weather for, e.g. San Francisco, CA"))
             .build();
 
+    ToolSpecification toolWithoutParameter = ToolSpecification.builder()
+            .name("get_current_time")
+            .description("Get the current time")
+            .build();
+
     ChatLanguageModel ollamaChatModel = OllamaChatModel.builder()
             .baseUrl(ollama.getEndpoint())
             .modelName(TOOL_MODEL)
@@ -90,4 +96,22 @@ class OllamaToolChatModelIT extends AbstractOllamaToolsLanguageModelInfrastructu
         assertThat(aiMessage.toolExecutionRequests()).isNull();
     }
 
+    @Test
+    void should_handle_tool_without_parameter() {
+
+        // given
+        List<ToolSpecification> toolSpecifications = singletonList(toolWithoutParameter);
+
+        // when
+        List<ChatMessage> chatMessages = singletonList(
+                userMessage("What is the current time?")
+        );
+
+        // then
+        assertDoesNotThrow(() -> {
+            ollamaChatModel.generate(chatMessages, toolSpecifications);
+        });
+
+    }
+
 }
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