diff --git a/.gitignore b/.gitignore
index 56823d2..533d3d8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,7 +5,7 @@
 *.pyc
 *.pyd
 /javabridge/jars/*java2cpython.*
-/javabridge/_javabridge.so
+/javabridge/*.so
 /python_javabridge.egg-info
 /docs/_build
 *.class
@@ -17,3 +17,4 @@
 /docs/build
 /javabridge.egg-info
 /javabridge/_version.py
+.coverage
\ No newline at end of file
diff --git a/_javabridge.pyx b/_javabridge.pyx
index 8e0774d..756ec67 100644
--- a/_javabridge.pyx
+++ b/_javabridge.pyx
@@ -1,3 +1,4 @@
+# cython: language_level=3
 """_javabridge.pyx - low-level interface to the JVM
 
 python-javabridge is licensed under the BSD license.  See the
@@ -798,7 +799,7 @@ cdef class JB_Env:
         utf8name = name.encode('utf-8')
         c = self.env[0].FindClass(self.env, utf8name)
         if c == NULL:
-            print "Failed to get class "+name
+            print("Failed to get class "+name)
             return
         cref = self.env[0].NewGlobalRef(self.env, c)
         if cref == NULL:
@@ -1640,7 +1641,7 @@ cdef class JB_Env:
             jsize nchars
             jobject o
         u16 = u.encode("utf-16")
-        nchars = len(u16) / 2 - 1
+        nchars = len(u16) // 2 - 1
         s = u16
         o = self.env[0].NewString(self.env, <jchar *>s+1, nchars)
         if o == NULL:
diff --git a/java/org/cellprofiler/javabridge/test/TestCPython.java b/java/org/cellprofiler/javabridge/test/TestCPython.java
index 8244ecf..07ef495 100644
--- a/java/org/cellprofiler/javabridge/test/TestCPython.java
+++ b/java/org/cellprofiler/javabridge/test/TestCPython.java
@@ -18,7 +18,7 @@ public class TestCPython {
 	@Test
 	public void test_01_01_exec() {
 		try {
-			new CPython().exec("print 'Hello, world.'\n");
+			new CPython().exec("print('Hello, world.')\n");
 		} catch (CPython.WrappedException e) {
 			fail();
 		}
@@ -33,15 +33,15 @@ public void test_02_01_threading() {
 		String code = 
 				"import javabridge\n" +
 				"import threading\n" +
-				"print 'yes I did run'\n" +
+				"print('yes I did run')\n" +
 				"def do_something()\n" +
-				"  print 'from inside thread'\n" +
+				"  print('from inside thread')\n" +
 				"  system = javabridge.JClassWrapper('java.lang.System')\n" +
 				"  system.setProperty('foo', 'bar')\n" +
 				"thread=threading.Thread(target=do_something)\n" +
 				"thread.start()\n" +
 				"thread.join()\n" +
-				"print 'yes I did finish'\n";
+				"print('yes I did finish')\n";
 		try {
 			System.out.print(code);
 			new CPython().exec(code);
diff --git a/java/org_cellprofiler_javabridge_CPython.c b/java/org_cellprofiler_javabridge_CPython.c
index acef41b..9a13ce7 100644
--- a/java/org_cellprofiler_javabridge_CPython.c
+++ b/java/org_cellprofiler_javabridge_CPython.c
@@ -71,7 +71,7 @@ JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved)
 #ifdef __linux__
     char buf[1024];
     char *python_location = get_property(vm, "python.location");
-    const char *command = "python -c \"import sysconfig; from os.path import join; print join(sysconfig.get_config_var('LIBDIR'), sysconfig.get_config_var('multiarchsubdir')[1:], sysconfig.get_config_var('LDLIBRARY'))\"";
+    const char *command = "python -c \"import sysconfig; from os.path import join; print(join(sysconfig.get_config_var('LIBDIR'), sysconfig.get_config_var('multiarchsubdir')[1:], sysconfig.get_config_var('LDLIBRARY')))\"";
 
     if (!python_location) {
 	size_t len=1024;