Index: netpbm-10.86.3/converter/other/pngx.c
===================================================================
--- netpbm-10.86.3.orig/converter/other/pngx.c	2019-05-14 09:27:19.536073096 +0200
+++ netpbm-10.86.3/converter/other/pngx.c	2019-05-14 09:27:21.976084785 +0200
@@ -368,6 +368,7 @@ pngx_srgbIntentDesc(pngx_srgbIntent cons
     case PNGX_ABSOLUTE_COLORIMETRIC: return "ABSOLUTE_COLORIMETRIC";
     }
     assert(false);
+    return NULL;
 }
 
 
@@ -383,6 +384,7 @@ const libpngSrgbIntentCode(pngx_srgbInte
     }
 
     assert(false);  /* All cases above return */
+    return -1;
 }
 
 
Index: netpbm-10.86.3/editor/pbmreduce.c
===================================================================
--- netpbm-10.86.3.orig/editor/pbmreduce.c	2019-05-14 09:27:21.952084670 +0200
+++ netpbm-10.86.3/editor/pbmreduce.c	2019-05-14 09:27:21.976084785 +0200
@@ -202,6 +202,9 @@ oppositeDir(enum Direction const arg) {
     case RIGHT_TO_LEFT: return LEFT_TO_RIGHT;
     }
     assert(false);  /* All cases handled above */
+
+    /* make gcc happy */
+    return RIGHT_TO_LEFT;
 }
 
 
Index: netpbm-10.86.3/lib/libpm.c
===================================================================
--- netpbm-10.86.3.orig/lib/libpm.c	2019-05-14 09:27:21.956084689 +0200
+++ netpbm-10.86.3/lib/libpm.c	2019-05-14 09:27:21.976084785 +0200
@@ -440,6 +440,7 @@ pm_maxvaltobits(int const maxval) {
         pm_error( "maxval of %d is too large!", maxval );
 
     assert(false);
+    return 0;
 }
 
 int
Index: netpbm-10.86.3/lib/libpnm3.c
===================================================================
--- netpbm-10.86.3.orig/lib/libpnm3.c	2019-05-14 09:16:33.096977241 +0200
+++ netpbm-10.86.3/lib/libpnm3.c	2019-05-14 11:07:02.148770284 +0200
@@ -429,6 +429,8 @@ pnm_bittoxel(bit    const inputBit,
     case PBM_WHITE: return pnm_whitexel(maxval, PBM_TYPE); break;
     default:
         assert(false);
+        pixel const black = {0, 0, 0};
+        return black;
     }
 }