diff --git a/core/CCBool.ml b/core/CCBool.ml
index b890edeb..0712e58b 100644
--- a/core/CCBool.ml
+++ b/core/CCBool.ml
@@ -26,9 +26,9 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 type t = bool
 
-let equal a b = a=b
+let equal (a:bool) b = a=b
 
-let compare a b = Pervasives.compare a b
+let compare (a:bool) b = Pervasives.compare a b
 
 let negate x = not x
 
diff --git a/core/CCInt.ml b/core/CCInt.ml
index a5689aa5..57e0c2dc 100644
--- a/core/CCInt.ml
+++ b/core/CCInt.ml
@@ -26,9 +26,9 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 type t = int
 
-let equal a b = a=b
+let equal (a:int) b = a=b
 
-let compare a b = Pervasives.compare a b
+let compare (a:int) b = Pervasives.compare a b
 
 let hash i = i land max_int
 
diff --git a/core/CCString.ml b/core/CCString.ml
index 1128093a..96023ea0 100644
--- a/core/CCString.ml
+++ b/core/CCString.ml
@@ -50,7 +50,7 @@ end
 
 type t = string
 
-let equal a b = a=b
+let equal (a:string) b = a=b
 
 let compare = String.compare