diff --git a/src/primitives.c b/src/primitives.c
index d50069d8..03c2e7a0 100644
--- a/src/primitives.c
+++ b/src/primitives.c
@@ -176,10 +176,9 @@ DEF_PRIMITIVE(string_contains)
   const char* search = AS_CSTRING(args[1]);
 
   // Corner case, the empty string contains the empty string.
-  if (strlen(string) == 0 && strlen(search) == 0) return NUM_VAL(1);
+  if (strlen(string) == 0 && strlen(search) == 0) return TRUE_VAL;
 
-  // TODO(bob): Return bool.
-  return NUM_VAL(strstr(string, search) != NULL);
+  return BOOL_VAL(strstr(string, search) != NULL);
 }
 
 DEF_PRIMITIVE(string_count)
diff --git a/test/string_contains.wren b/test/string_contains.wren
index 1560a450..4145bc8a 100644
--- a/test/string_contains.wren
+++ b/test/string_contains.wren
@@ -1,8 +1,8 @@
-io.write("".contains(""))   // expect: 1
-io.write("anything".contains("")) // expect: 1
-io.write("something".contains("meth")) // expect: 1
-io.write("something".contains("some")) // expect: 1
-io.write("something".contains("ing")) // expect: 1
-io.write("something".contains("math")) // expect: 0
+io.write("".contains(""))              // expect: true
+io.write("anything".contains(""))      // expect: true
+io.write("something".contains("meth")) // expect: true
+io.write("something".contains("some")) // expect: true
+io.write("something".contains("ing"))  // expect: true
+io.write("something".contains("math")) // expect: false
 
 // TODO(bob): Passing non-string as argument.