diff --git a/src/main/kotlin/build/buf/gradle/BufSupport.kt b/src/main/kotlin/build/buf/gradle/BufSupport.kt
index a4da9ea1..14287ff5 100644
--- a/src/main/kotlin/build/buf/gradle/BufSupport.kt
+++ b/src/main/kotlin/build/buf/gradle/BufSupport.kt
@@ -16,6 +16,7 @@ package build.buf.gradle
 
 import org.gradle.api.Project
 import org.gradle.kotlin.dsl.dependencies
+import org.jetbrains.annotations.VisibleForTesting
 import java.nio.charset.StandardCharsets
 
 const val BUF_BINARY_CONFIGURATION_NAME = "bufTool"
@@ -80,15 +81,27 @@ internal fun AbstractBufExecTask.execBuf(
     logger.info("Running buf from $workingDirValue: `buf ${args.joinToString(" ")}`")
     val result = ProcessRunner().use { it.shell(workingDirValue, processArgs) }
 
+    handleResult(result, customErrorMessage)
+}
+
+@VisibleForTesting
+internal fun handleResult(
+    result: ProcessRunner.Result,
+    customErrorMessage: ((String) -> String)?,
+) {
     if (result.exitCode != 0) {
         if (customErrorMessage != null) {
             val stdOut = result.stdOut.toString(StandardCharsets.UTF_8)
             val stdErr = result.stdErr.toString(StandardCharsets.UTF_8)
-            val ex = IllegalStateException(customErrorMessage(stdOut))
-            if (stdErr.isNotEmpty()) {
-                ex.addSuppressed(IllegalStateException(result.toString()))
+            if (stdOut.isEmpty()) {
+                error(result.toString())
+            } else {
+                val ex = IllegalStateException(customErrorMessage(stdOut))
+                if (stdErr.isNotEmpty()) {
+                    ex.addSuppressed(IllegalStateException(result.toString()))
+                }
+                throw ex
             }
-            throw ex
         } else {
             error(result.toString())
         }
diff --git a/src/test/kotlin/build/buf/gradle/BufSupportTest.kt b/src/test/kotlin/build/buf/gradle/BufSupportTest.kt
new file mode 100644
index 00000000..df10e4f6
--- /dev/null
+++ b/src/test/kotlin/build/buf/gradle/BufSupportTest.kt
@@ -0,0 +1,38 @@
+// Copyright 2024 Buf Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package build.buf.gradle
+
+import com.google.common.truth.Truth.assertThat
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+
+class BufSupportTest {
+    @Test
+    fun `handleResult includes stderr when stdout is empty and custom error message is specified`() {
+        val thrown =
+            assertThrows<IllegalStateException> {
+                handleResult(
+                    ProcessRunner.Result(
+                        emptyList(),
+                        1,
+                        "".toByteArray(),
+                        "error that would be hidden".toByteArray(),
+                    ),
+                ) { "foo" }
+            }
+
+        assertThat(thrown).hasMessageThat().contains("error that would be hidden")
+    }
+}