diff --git a/CHANGES.md b/CHANGES.md
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,7 +1,12 @@
 * Hackage: <http://hackage.haskell.org/package/crackNum>
 * GitHub:  <http://github.com/LeventErkok/crackNum/>
 
-* Latest Hackage released version: 3.5, 2023-04-11
+* Latest Hackage released version: 3.6, 2024-01-24
+
+### Version 3.6, 2024-01-24
+  * Be more clear when the provided input isn't a recognizable float,
+    instead of treating it as NaN implicitly. Thanks to Dmitry Blotsky for
+    pointing out the confusion.
 
 ### Version 3.5, 2024-01-11
   * Resolve compilation issues with GHC 9.8 series
diff --git a/crackNum.cabal b/crackNum.cabal
--- a/crackNum.cabal
+++ b/crackNum.cabal
@@ -1,6 +1,6 @@
 Cabal-version      : 2.2
 Name               : crackNum
-Version            : 3.5
+Version            : 3.6
 Synopsis           : Crack various integer and floating-point data formats
 Description        : Crack IEEE-754 float formats and arbitrary sized words and integers, showing the layout.
                      .
@@ -26,7 +26,7 @@
    default-language: Haskell2010
    hs-source-dirs  : src
    ghc-options     : -Wall -Wunused-packages
-   build-depends   : base >= 4.11 && < 5, libBF, sbv >= 10.0
+   build-depends   : base >= 4.11 && < 5, libBF, sbv >= 10.3
                    , tasty, tasty-golden, filepath, directory, process
    other-modules   : Paths_crackNum, CrackNum.TestSuite
    autogen-modules : Paths_crackNum
diff --git a/src/CrackNum/Main.hs b/src/CrackNum/Main.hs
--- a/src/CrackNum/Main.hs
+++ b/src/CrackNum/Main.hs
@@ -360,12 +360,19 @@
                                             note $ snd $ convert 11 53
                   _                   -> ef (FP 11 53)
          where p :: Double -> Predicate
-               p d = do x <- sDouble"ENCODED"
+               p d = do x <- sDouble "ENCODED"
                         pure $ x .=== literal d
 
         ef (FP i j) = do let (v, mbS) = convert i j
-                         print =<< satWith z3{crackNum=True} (p v)
-                         note mbS
+                         if bfIsNaN v
+                            then die [ "Input does not represent floating point number we recognize."
+                                     , "Saw: " ++ inp
+                                     , ""
+                                     , "For decoding bit-strings, prefix them with 0x or 0b, and"
+                                     , "provide a hexadecimal or binary representation of the input."
+                                     ]
+                            else do print =<< satWith z3{crackNum=True} (p v)
+                                    note mbS
           where p :: BigFloat -> Predicate
                 p bf = do let k = KFP i j
                           sx <- svNewVar k "ENCODED"