diff --git a/BloomDBG/bloom-dbg.h b/BloomDBG/bloom-dbg.h
index 2b1b84b60..9e619a817 100644
--- a/BloomDBG/bloom-dbg.h
+++ b/BloomDBG/bloom-dbg.h
@@ -175,6 +175,7 @@ seedTypeStr(const SeedType& type)
 		break;
 	}
 	assert(false);
+	return "";
 }
 
 /**
@@ -288,6 +289,7 @@ readResultStr(const ReadResult& result)
 		break;
 	}
 	assert(false);
+	return "";
 }
 
 /**
@@ -460,7 +462,7 @@ printContig(
     unsigned k,
     std::ostream& out)
 {
-	assert(seq.length() >= k);
+	assert(seq.length() >= k); (void)k;
 
 	FastaRecord contig;
 
diff --git a/Graph/ExtendPath.h b/Graph/ExtendPath.h
index 540f18b74..4dbc4130a 100644
--- a/Graph/ExtendPath.h
+++ b/Graph/ExtendPath.h
@@ -76,6 +76,7 @@ static inline const char* pathExtensionResultStr(PathExtensionResultCode result)
 	default:
 		assert(false);
 	}
+	return "";
 }
 
 /** length of path extension (in vertices) and reason for stopping */
diff --git a/Konnector/konnector.cc b/Konnector/konnector.cc
index 85871e114..463c73480 100644
--- a/Konnector/konnector.cc
+++ b/Konnector/konnector.cc
@@ -457,7 +457,7 @@ static inline string calcQual(const FastqRecord& orig,
 	unsigned extendedRight)
 {
 	assert(extended.length() == orig.seq.length() +
-		extendedLeft + extendedRight);
+		extendedLeft + extendedRight); (void)extendedRight;
 
 	unsigned char correctedQual = opt::qualityOffset + opt::correctedQual;
 	string qual(extended.length(), correctedQual);