diff --git a/alib/src/regexp/Alternation.cpp b/alib/src/regexp/Alternation.cpp
index 81ff4f56fafce9c54c6968c92b424c3abceb9b58..180d2413f4e6058b7849209301ea624f7b3ddab9 100644
--- a/alib/src/regexp/Alternation.cpp
+++ b/alib/src/regexp/Alternation.cpp
@@ -109,9 +109,9 @@ bool Alternation::containsEmptyString() const {
 bool Alternation::isEmpty() const {
 	for(const auto& e : getElements())
 		if(!e->isEmpty())
-			return true;
+			return false;
 
-	return false;
+	return true;
 }
 
 } /* namespace regexp */
diff --git a/alib/src/regexp/Concatenation.cpp b/alib/src/regexp/Concatenation.cpp
index 602ebde3c8a4d2386d1e0151a8e82ce3d02a2807..d06806fcf2ee4a33a5d6e7a8c7f2d22611c69e17 100644
--- a/alib/src/regexp/Concatenation.cpp
+++ b/alib/src/regexp/Concatenation.cpp
@@ -104,10 +104,10 @@ bool Concatenation::containsEmptyString() const {
 
 bool Concatenation::isEmpty() const {
 	for(const auto& e : getElements())
-		if(!e->isEmpty())
-			return false;
+		if(e->isEmpty())
+			return true;
 
-	return true;
+	return false;
 }
 
 } /* namespace regexp */