diff --git a/imageio/imageio-pnm/src/main/java/com/twelvemonkeys/imageio/plugins/pnm/PNMImageWriter.java b/imageio/imageio-pnm/src/main/java/com/twelvemonkeys/imageio/plugins/pnm/PNMImageWriter.java
index b7af9314..37ac662b 100755
--- a/imageio/imageio-pnm/src/main/java/com/twelvemonkeys/imageio/plugins/pnm/PNMImageWriter.java
+++ b/imageio/imageio-pnm/src/main/java/com/twelvemonkeys/imageio/plugins/pnm/PNMImageWriter.java
@@ -65,6 +65,7 @@ public final class PNMImageWriter extends ImageWriterBase {
 
     @Override
     public void write(final IIOMetadata streamMetadata, final IIOImage image, final ImageWriteParam param) throws IOException {
+        assertOutput();
         // TODO: Issue warning if streamMetadata is non-null?
         // TODO: Issue warning if IIOImage contains thumbnails or other data we can't store?
 
diff --git a/imageio/imageio-pnm/src/test/java/com/twelvemonkeys/imageio/plugins/pnm/PNMImageReaderTest.java b/imageio/imageio-pnm/src/test/java/com/twelvemonkeys/imageio/plugins/pnm/PNMImageReaderTest.java
index 49755bdc..390141e3 100755
--- a/imageio/imageio-pnm/src/test/java/com/twelvemonkeys/imageio/plugins/pnm/PNMImageReaderTest.java
+++ b/imageio/imageio-pnm/src/test/java/com/twelvemonkeys/imageio/plugins/pnm/PNMImageReaderTest.java
@@ -55,7 +55,8 @@ public class PNMImageReaderTest extends ImageReaderAbstractTest<PNMImageReader>
                 new TestData(getClassLoaderResource("/pgm/house.l.pgm"), new Dimension(367, 241)),  // P5 (PGM RAW)
                 new TestData(getClassLoaderResource("/ppm/lighthouse_rgb48.ppm"), new Dimension(768, 512)),  // P6 (PPM RAW, 16 bits/sample)
                 new TestData(getClassLoaderResource("/pam/lena.pam"), new Dimension(128, 128)),     // P7 RGB
-                new TestData(getClassLoaderResource("/pam/rgba.pam"), new Dimension(4, 2))          // P7 RGB_ALPHA
+                new TestData(getClassLoaderResource("/pam/rgba.pam"), new Dimension(4, 2)),         // P7 RGB_ALPHA
+                new TestData(getClassLoaderResource("/pfm/memorial.pfm"), new Dimension(512, 768))  // PF (32 bits/sample, floating point)
         );
     }
 
diff --git a/imageio/imageio-pnm/src/test/java/com/twelvemonkeys/imageio/plugins/pnm/PNMImageWriterTest.java b/imageio/imageio-pnm/src/test/java/com/twelvemonkeys/imageio/plugins/pnm/PNMImageWriterTest.java
new file mode 100644
index 00000000..7b76fde1
--- /dev/null
+++ b/imageio/imageio-pnm/src/test/java/com/twelvemonkeys/imageio/plugins/pnm/PNMImageWriterTest.java
@@ -0,0 +1,29 @@
+package com.twelvemonkeys.imageio.plugins.pnm;
+
+import com.twelvemonkeys.imageio.util.ImageWriterAbstractTest;
+
+import javax.imageio.ImageWriter;
+import java.awt.image.BufferedImage;
+import java.awt.image.RenderedImage;
+import java.util.Arrays;
+import java.util.List;
+
+public class PNMImageWriterTest extends ImageWriterAbstractTest {
+
+    private final PNMImageWriterSpi provider = new PNMImageWriterSpi();
+
+    @Override
+    protected ImageWriter createImageWriter() {
+        return provider.createWriterInstance(null);
+    }
+
+    @Override
+    protected List<? extends RenderedImage> getTestData() {
+        return Arrays.asList(
+                new BufferedImage(100, 100, BufferedImage.TYPE_3BYTE_BGR),
+                new BufferedImage(100, 100, BufferedImage.TYPE_BYTE_GRAY),
+                new BufferedImage(100, 100, BufferedImage.TYPE_USHORT_GRAY),
+                new BufferedImage(100, 100, BufferedImage.TYPE_4BYTE_ABGR)
+        );
+    }
+}
\ No newline at end of file