diff --git a/src/V3Number.h b/src/V3Number.h
index 5541c33e6..cf2700185 100644
--- a/src/V3Number.h
+++ b/src/V3Number.h
@@ -56,10 +56,19 @@ public:
     V3Number& setDouble(double value);
     void setBit (int bit, char value) {		// Note must be pre-zeroed!
 	if (bit>=m_width) return;
-	if (value=='0'||value==0)                       m_value [bit/32] &= ~(1UL<<(bit&31));
-	else {
-	    if (value=='1'||value=='x'||value==1||value==3) m_value [bit/32] |= (1UL<<(bit&31));
-	    if (value=='z'||value=='x'||value==2||value==3) m_valueX[bit/32] |= (1UL<<(bit&31));
+	uint32_t mask = (1UL<<(bit&31));
+	if (value=='0' || value==0) {
+	    m_value [bit/32] &= ~mask;
+	    m_valueX[bit/32] &= ~mask;
+	} else if (value=='1'|| value==1) {
+	    m_value [bit/32] |=  mask;
+	    m_valueX[bit/32] &= ~mask;
+	} else if (value=='z'|| value==3) {
+	    m_value [bit/32] &= ~mask;
+	    m_valueX[bit/32] |=  mask;
+	} else { // X
+	    m_value [bit/32] |=  mask;
+	    m_valueX[bit/32] |=  mask;
 	}
     }
 private: