diff --git a/src/KIM/kim_interactions.cpp b/src/KIM/kim_interactions.cpp
index 87be2a4e7e..a91c615d09 100644
--- a/src/KIM/kim_interactions.cpp
+++ b/src/KIM/kim_interactions.cpp
@@ -256,7 +256,7 @@ void KimInteractions::KIM_SET_TYPE_PARAMETERS(const std::string &input_line) con
   std::string key = words[1];
   std::string filename = words[2];
   std::vector<std::string> species(words.begin()+3,words.end());
-  if (species.size() != atom->ntypes)
+  if ((int)species.size() != atom->ntypes)
     error->one(FLERR,"Incorrect args for KIM_SET_TYPE_PARAMETERS command");
 
   FILE *fp;
diff --git a/src/MISC/dump_xtc.cpp b/src/MISC/dump_xtc.cpp
index 12fc57dd4b..022591839f 100644
--- a/src/MISC/dump_xtc.cpp
+++ b/src/MISC/dump_xtc.cpp
@@ -651,12 +651,12 @@ static void sendints(int buf[], const int num_of_ints, const int num_of_bits,
     num_of_bytes = bytecnt;
   }
   if (num_of_bits >= (int)num_of_bytes * 8) {
-    for (i = 0; i < num_of_bytes; i++) {
+    for (i = 0; i < (int)num_of_bytes; i++) {
       sendbits(buf, 8, bytes[i]);
     }
     sendbits(buf, num_of_bits - num_of_bytes * 8, 0);
   } else {
-    for (i = 0; i < num_of_bytes-1; i++) {
+    for (i = 0; i < (int)num_of_bytes-1; i++) {
       sendbits(buf, 8, bytes[i]);
     }
     sendbits(buf, num_of_bits- (num_of_bytes -1) * 8, bytes[i]);
@@ -691,7 +691,7 @@ static int receivebits(int buf[], int num_of_bits)
     num_of_bits -=8;
   }
   if (num_of_bits > 0) {
-    if (lastbits < num_of_bits) {
+    if ((int)lastbits < num_of_bits) {
       lastbits += 8;
       lastbyte = (lastbyte << 8) | cbuf[cnt++];
     }
@@ -931,11 +931,11 @@ int xdr3dfcoord(XDR *xdrs, float *fp, int *size, float *precision)
     lip = ip;
     luip = (unsigned int *) ip;
     smallidx = FIRSTIDX;
-    while (smallidx < LASTIDX && magicints[smallidx] < mindiff) {
+    while (smallidx < (int)LASTIDX && magicints[smallidx] < mindiff) {
       smallidx++;
     }
     xdr_int(xdrs, &smallidx);
-    maxidx = MYMIN(LASTIDX, smallidx + 8) ;
+    maxidx = MYMIN((int)LASTIDX, smallidx + 8) ;
     minidx = maxidx - 8; /* often this equal smallidx */
     smaller = magicints[MYMAX(FIRSTIDX, smallidx-1)] / 2;
     small = magicints[smallidx] / 2;
@@ -1111,7 +1111,7 @@ int xdr3dfcoord(XDR *xdrs, float *fp, int *size, float *precision)
     }
 
     xdr_int(xdrs, &smallidx);
-    maxidx = MYMIN(LASTIDX, smallidx + 8) ;
+    maxidx = MYMIN((int)LASTIDX, smallidx + 8) ;
     minidx = maxidx - 8; /* often this equal smallidx */
     smaller = magicints[MYMAX(FIRSTIDX, smallidx-1)] / 2;
     small = magicints[smallidx] / 2;
diff --git a/src/USER-DPD/fix_rx.cpp b/src/USER-DPD/fix_rx.cpp
index 4928c2c0e2..77efd1842b 100644
--- a/src/USER-DPD/fix_rx.cpp
+++ b/src/USER-DPD/fix_rx.cpp
@@ -561,7 +561,7 @@ void FixRX::initSparse()
         if (SparseKinetics_enableIntegralReactions){
           sparseKinetics_inu[i][idx] = (int) sparseKinetics_nu[i][idx];
           if (isIntegral_i){
-            if (sparseKinetics_inu[i][idx] >= nu_bin.size())
+            if (sparseKinetics_inu[i][idx] >= (int)nu_bin.size())
                nu_bin.resize( sparseKinetics_inu[i][idx] );
 
             nu_bin[ sparseKinetics_inu[i][idx] ] ++;
diff --git a/src/USER-REAXC/reaxc_lookup.cpp b/src/USER-REAXC/reaxc_lookup.cpp
index 4c532db23e..5ca4a30b8c 100644
--- a/src/USER-REAXC/reaxc_lookup.cpp
+++ b/src/USER-REAXC/reaxc_lookup.cpp
@@ -68,22 +68,22 @@ void Natural_Cubic_Spline( LAMMPS_NS::Error* error_ptr, const double *h, const d
     a[i] = h[i-1];
 
   b[0] = b[n-1] = 0;
-  for( i = 1; i < n-1; ++i )
+  for( i = 1; i < (int)n-1; ++i )
     b[i] = 2 * (h[i-1] + h[i]);
 
   c[0] = c[n-2] = c[n-1] = 0;
-  for( i = 1; i < n-2; ++i )
+  for( i = 1; i < (int)n-2; ++i )
     c[i] = h[i];
 
   d[0] = d[n-1] = 0;
-  for( i = 1; i < n-1; ++i )
+  for( i = 1; i < (int)n-1; ++i )
     d[i] = 6 * ((f[i+1]-f[i])/h[i] - (f[i]-f[i-1])/h[i-1]);
 
   v[0] = 0;
   v[n-1] = 0;
   Tridiagonal_Solve( &(a[1]), &(b[1]), &(c[1]), &(d[1]), &(v[1]), n-2 );
 
-  for( i = 1; i < n; ++i ){
+  for( i = 1; i < (int)n; ++i ){
     coef[i-1].d = (v[i] - v[i-1]) / (6*h[i-1]);
     coef[i-1].c = v[i]/2;
     coef[i-1].b = (f[i]-f[i-1])/h[i-1] + h[i-1]*(2*v[i] + v[i-1])/6;
@@ -114,25 +114,25 @@ void Complete_Cubic_Spline( LAMMPS_NS::Error* error_ptr, const double *h, const
 
   /* build the linear system */
   a[0] = 0;
-  for( i = 1; i < n; ++i )
+  for( i = 1; i < (int)n; ++i )
     a[i] = h[i-1];
 
   b[0] = 2*h[0];
-  for( i = 1; i < n; ++i )
+  for( i = 1; i < (int)n; ++i )
     b[i] = 2 * (h[i-1] + h[i]);
 
   c[n-1] = 0;
-  for( i = 0; i < n-1; ++i )
+  for( i = 0; i < (int)n-1; ++i )
     c[i] = h[i];
 
   d[0] = 6 * (f[1]-f[0])/h[0] - 6 * v0;
   d[n-1] = 6 * vlast - 6 * (f[n-1]-f[n-2]/h[n-2]);
-  for( i = 1; i < n-1; ++i )
+  for( i = 1; i < (int)n-1; ++i )
     d[i] = 6 * ((f[i+1]-f[i])/h[i] - (f[i]-f[i-1])/h[i-1]);
 
   Tridiagonal_Solve( &(a[0]), &(b[0]), &(c[0]), &(d[0]), &(v[0]), n );
 
-  for( i = 1; i < n; ++i ){
+  for( i = 1; i < (int)n; ++i ){
     coef[i-1].d = (v[i] - v[i-1]) / (6*h[i-1]);
     coef[i-1].c = v[i]/2;
     coef[i-1].b = (f[i]-f[i-1])/h[i-1] + h[i-1]*(2*v[i] + v[i-1])/6;