diff --git a/src/core/compile.js b/src/core/compile.js
index 83363d6f..59696dad 100644
--- a/src/core/compile.js
+++ b/src/core/compile.js
@@ -33,9 +33,9 @@ export let compile = (str, defs, data) => {
                 // Here we check if this is strictly a boolean with false value
                 // define it as `''` to be picked up as empty, otherwise use
                 // res value
-                tail = res === false ? '' : res;
+                tail = res;
             }
         }
-        return out + next + (tail == null ? '' : tail);
+        return out + next + (tail == null || tail === false ? '' : tail);
     }, '');
 };
diff --git a/src/core/hash.js b/src/core/hash.js
index 6d3b5143..c37fa0b5 100644
--- a/src/core/hash.js
+++ b/src/core/hash.js
@@ -40,21 +40,28 @@ export let hash = (compiled, sheet, global, append, keyframes) => {
     let className =
         cache[stringifiedCompiled] || (cache[stringifiedCompiled] = toHash(stringifiedCompiled));
 
-    // If there's no entry for the current className
-    if (!cache[className]) {
-        // Build the _ast_-ish structure if needed
-        let ast = stringifiedCompiled !== compiled ? compiled : astish(compiled);
-
-        // Parse it
-        cache[className] = parse(
-            // For keyframes
-            keyframes ? { ['@keyframes ' + className]: ast } : ast,
-            global ? '' : '.' + className
-        );
-    }
-
     // add or update
-    update(cache[className], sheet, append);
+    update(
+        (cache[className] =
+            cache[className] ||
+            // If there's no entry for the current className
+            // Parse it
+            parse(
+                // For keyframes
+                keyframes
+                    ? // Build the _ast_-ish structure if needed
+                      {
+                          ['@keyframes ' + className]:
+                              stringifiedCompiled !== compiled ? compiled : astish(compiled)
+                      }
+                    : stringifiedCompiled !== compiled
+                    ? compiled
+                    : astish(compiled),
+                global ? '' : '.' + className
+            )),
+        sheet,
+        append
+    );
 
     // return hash
     return className;
diff --git a/src/core/parse.js b/src/core/parse.js
index fb05f852..90250557 100644
--- a/src/core/parse.js
+++ b/src/core/parse.js
@@ -43,7 +43,7 @@ export let parse = (obj, selector) => {
                       })
                     : key
             );
-        } else if (val != undefined) {
+        } else if (val +1 ) {
             // Convert all but CSS variables
             key = /^--/.test(key) ? key : key.replace(/[A-Z]/g, '-$&').toLowerCase();
             // Push the line for this property
diff --git a/src/core/update.js b/src/core/update.js
index bc21891c..f8a4b058 100644
--- a/src/core/update.js
+++ b/src/core/update.js
@@ -17,5 +17,5 @@ export let extractCss = (target) => {
  * @param {Boolean} append
  */
 export let update = (css, sheet, append) => {
-    sheet.data.indexOf(css) == -1 && (sheet.data = append ? css + sheet.data : sheet.data + css);
+    ~sheet.data.indexOf(css) || (sheet.data = append ? css + sheet.data : sheet.data + css);
 };
diff --git a/src/styled.js b/src/styled.js
index 65bd6682..8b3b240e 100644
--- a/src/styled.js
+++ b/src/styled.js
@@ -48,15 +48,11 @@ function styled(tag, forwardRef) {
             }
 
             // Assign the _as with the provided `tag` value
-            let _as = tag;
-
             // If this is a string -- checking that is has a first valid char
-            if (tag[0]) {
-                // Try to assign the _as with the given _as value if any
-                _as = _props.as || tag;
-                // And remove it
-                delete _props.as;
-            }
+            // Try to assign the _as with the given _as value if any
+            let _as = (tag[0] && _props.as) || tag;
+            // And remove it
+            tag[0] && delete _props.as;
 
             // Handle the forward props filter if defined and _as is a string
             if (fwdProp && _as[0]) {