diff --git a/include/gtkwave/fastlz.c b/include/gtkwave/fastlz.c
index 50bf56a46..3d2c3dc1e 100644
--- a/include/gtkwave/fastlz.c
+++ b/include/gtkwave/fastlz.c
@@ -418,7 +418,9 @@ static FASTLZ_INLINE int FASTLZ_DECOMPRESSOR(const void* input, int length, void
   const flzuint8* ip = (const flzuint8*) input;
   const flzuint8* ip_limit  = ip + length;
   flzuint8* op = (flzuint8*) output;
+#ifdef FASTLZ_SAFE
   flzuint8* op_limit = op + maxout;
+#endif
   flzuint32 ctrl = (*ip++) & 31;
   int loop = 1;
 
diff --git a/src/V3AstNodes.cpp b/src/V3AstNodes.cpp
index 17ccc32ee..27a0c46ed 100644
--- a/src/V3AstNodes.cpp
+++ b/src/V3AstNodes.cpp
@@ -290,6 +290,7 @@ string AstVar::vlArgType(bool named, bool forReturn, bool forFunc) const {
         if (mayparen) { oname = " ("+oname+")"; mayparen = false; }
         oarray += "["+cvtToStr(widthWords())+"]";
     }
+    if (mayparen) { }
     return otype+oname+oarray;
 }
 
diff --git a/src/V3File.cpp b/src/V3File.cpp
index 36584052b..4eb8401bb 100644
--- a/src/V3File.cpp
+++ b/src/V3File.cpp
@@ -223,7 +223,7 @@ inline bool V3FileDependImp::checkTimes(const string& filename, const string& cm
         return false;
     }
     {
-        string ignore = V3Os::getline(*ifp);
+        string ignore = V3Os::getline(*ifp);  if (ignore.empty()) { /*used*/ }
     }
     {
         char   chkDir;   *ifp>>chkDir;
diff --git a/src/V3Number.cpp b/src/V3Number.cpp
index e595d493b..a915fa65e 100644
--- a/src/V3Number.cpp
+++ b/src/V3Number.cpp
@@ -355,7 +355,7 @@ V3Number& V3Number::setLong(uint32_t value) {
 V3Number& V3Number::setLongS(vlsint32_t value) {
     for (int i=0; i<words(); i++) m_value[i]=m_valueX[i] = 0;
     union { uint32_t u; vlsint32_t s; } u;
-    u.s = value;
+    u.s = value; if (u.s) { }
     m_value[0] = u.u;
     opCleanThis();
     return *this;
@@ -366,7 +366,7 @@ V3Number& V3Number::setDouble(double value) {
     }
     m_double = true;
     union { double d; uint32_t u[2]; } u;
-    u.d = value;
+    u.d = value; if (u.d) { }
     for (int i=2; i<words(); i++) m_value[i]=m_valueX[i] = 0;
     m_value[0] = u.u[0]; m_value[1] = u.u[1];
     return *this;
diff --git a/src/V3Partition.cpp b/src/V3Partition.cpp
index fcf09ed94..b85532df2 100644
--- a/src/V3Partition.cpp
+++ b/src/V3Partition.cpp
@@ -1388,7 +1388,7 @@ private:
             donorp = fromp;
             recipientp = top;
         }
-        fromp = top = NULL;  // Use donorp and recipientp now instead
+        VL_DANGLING(fromp); VL_DANGLING(top);  // Use donorp and recipientp now instead
 
         // Recursively update forward and reverse CP numbers.
         //
diff --git a/test_regress/t/t_dpi_export_c.cpp b/test_regress/t/t_dpi_export_c.cpp
index dba8b9901..df87236e4 100644
--- a/test_regress/t/t_dpi_export_c.cpp
+++ b/test_regress/t/t_dpi_export_c.cpp
@@ -75,10 +75,9 @@ extern "C" {
     if ((got) != (exp)) {                       \
         printf("%%Error: %s:%d:", __FILE__,__LINE__);   \
         union { type a; long long l; } u;       \
-        u.l = 0; u.a = got;                     \
-        if (u.a) { } /*not unused*/             \
+        u.l = 0; u.a = got; if (u.a) {/*used*/} \
         printf(" GOT = %" T_PRI64 "x", u.l);    \
-        u.l = 0; u.a = exp;                     \
+        u.l = 0; u.a = exp; if (u.a) {/*used*/} \
         printf("  EXP = %" T_PRI64 "x\n", u.l); \
         return __LINE__; \
     }